Acute myelogenous leukemia; Acute nonlymphocytic leukemia; Agranular CD4+ CD56+ hematodermic neoplasm; Agranular CD4+ NK cell leukemia; Blastic NK cell lymphoma; Blastic NK leukemia/lymphoma Acute Myeloid Leukemia (AML) is a bone marrow cancer, characterized by the clonal expansion and lack of differentiation of early myeloid cells. In the majority of cases, the diagnosis of AML requires a myeloid blast count ≥20% of nucleated cells in the blood or bone marrow. Blasts can also infiltrate other organs or tissues such as skin, gums, or lymph nodes. Rarely AML can present as an isolated myeloid sarcoma in any tissue. The definition of myeloid blasts includes abnormal promyelocytes in acute promyelocytic leukemia (APL), and promonocytes in monocytic/monoblastic AML. Almost any myeloid lineage can be affected; myeloid or monocytic are relatively common, but rare basophilic, pure erythroid and megakaryocytic forms of AML exist. AML is an extremely heterogeneous disease, with many distinct subgroups defined by specific morphological, cytogenetic, molecular, and gene expression characteristics. The World Health Organisation (WHO) has classified AML according to some of the most significant clinical, morphological, cytogenetic, and molecular pathological factors (ref) (Table 1). Other subgroups include AML with myelodysplasia-related changes, therapy-related myeloid neoplasms, myeloid sarcoma, and myeloid proliferations related to Down Syndrome. The WHO classification has largely replaced the earlier French American British (FAB) classification, which was principally based on morphological characteristics. A morphological classification does remain, in the AML not otherwise specified (AML NOS) WHO subgroup, which is used if no other defining features are present. Table 1 WHO classification of AML and related neoplasms WHO subtype Morphology Immunophenotype Molecular/Other AML with recurrent genetic abnormalities AML with t(8;21)(q22;q22); RUNX1-RUNX1T1 Blasts >5%. Large blasts with granulation and auer rods. Most commonly AML with maturation (see below), often with dysplastic features in maturing cells. Occasionally absence of maturation or rarely monocytic differentiation CD34+, CD13+, CD33+, HLA-DR+, MPO+ Subpopulation with CD15+ (maturing granulocytes) Often aberrant CD19+, more rarely CD56+ Additional chromosomal abnormalities in 70%. KRAS/NRAS mutations in 30% pediatric cases KIT mutations in 20–25% 10 year survival 61% AML with inv(16)(p13;q22) or t(16;16)(p13;q22); CBFB-MYH11 Blasts >5%. Morphological features of myelomonocytic leukemia (see below). Abnormal eosinophil component in the BM (large purple-red granules in immature forms). Rarely lack eosinophilia or show myeloid or monoctyic differentiation only Multiple CD34+, CD117+ blast populations Granulocytic: CD13+, CD33+, CD15+, MPO+ Monocytic: CD14+, CD11b+, CD11c+, CD64+, CD36+ Often aberrant expression CD2 Inv(16) more common that t(16;16) Additional chromosomal abnormalities in 40%, trisomy 22 fairly specific KIT mutations in 30% 10 year survival 55% APL with PML-RARA Atypical promyelocytes >5%. Hypergranular variant with prominent red-purple granules (rare in PB). Some cells contain bundles of auer rods (faggot cells). Microgranular variant with more readily visible dumbbell or bilobed nucleus and high PB count CD13+, CD33+, MPO+, HLA-DR−, CD34− Aberrant expression CD2 in microgranular variant Additional chromosomal abnormalities in 40%, with trisomy 8 the most common Mutations in FLT3 ITD or TKD in 35–45% 10 year survival 73% AML with t(9;11)(p21;q23); MLLT3-KMT2A Blasts ≥20%. Morphological features most often monocytic or myelomonocytic (see below). Occasionally AML with or without maturation In children: CD33+, CD65+, CD4+, HLA-DR+ CD13−/+, CD34−/+, CD14 −/+ In adults: markers of monocytic differentiation – CD14+, CD4+, CD11b+, CD11c+, CD64+, CD36+. Variable expression CD34, CD117, CD56 Secondary cytogenetic abnormalities are frequent, with trisomy 8 the most common 10 year survival 39% AML with t(6;9)(p23;q34); DEK-NUP214 Blasts ≥20%. Most commonly AML with maturation or acute myelomonocytic leukemia (see below). Can have morphological features of any FAB subtype other than APL or acute megakaryoblastic leukemia. Marrow and PB basophilia in approximately 50% cases MPO+, CD13+, CD33+, HLA-DR+ CD117±, CD34±, CD15± Tdt + in 50% The t(6;9) translocation is the sole chromosomal abnormality in most cases. The fusion protein acts as an aberrant transcription factor FLT3-ITD very common 69%–78% cases 10 year survival 26% AML with inv(3)(q21;q26) or t(3;3)(q21;q26); GATA2, MECOM Blasts ≥20%. Most commonly AML without maturation, acute myelomonocytic leukemia or acute megakaryoblastic leukemia. Can have morphological features of any FAB subtype other than APL. PB may have dysplastic neutrophils, giant and hypogranular platelets. Multilineage dysplasia is common in the BM CD13+, CD33+, HLA-DR+, CD34+, CD38 + Some aberrant CD7 expression. Some with megakaryocytic marker expression (CD41 and CD61) Repositioning distal GATA2 enhancer. MECOM activation and haploinsufficiency GATA2 10 year survival 3%. AML (megakaryoblastic) with t(1;22)(p13;q13) Blasts ≥20%. Morphologically acute megakaryoblastic leukemia. Fibrosis usually present. Occurs exclusively in infant and children <3 years Megakaryocyte markers: CD41+ and/or CD61+. CD36 + Often CD34−, MPO− and HLA-DR− The t(1;22) translocation is the sole chromosomal abnormality in most cases. The fusion gene may modulate chromatin organization Provisional: AML with BCR-ABL1 Blasts ≥20%. May present as de novo disease or result from blast crisis of CML CD13+, CD33+, MPO+ Preliminary data suggest deletion of IGH, TCR, IKZF1 or CDKN2A may support a diagnosis of de novo disease vs. CML blast phase Unfavorable prognosis AML with mutated NPM1 Blasts ≥20%. Most commonly myelomonocytic or monocytic (80–90% of acute monocytic leukemias have an NPM1 mutation). NPM1 mutations are also seen in AML with and without maturation. Some have multilineage dysplasia. WCC usually high CD13+, CD33+, MPO+, CD34− Monocytic markers common: CD14+, CD11b+, CD68+ Abnormal karyotype in only 5–15%. NPM1 mutations usually mutually exclusive of balanced translocations that define AML entities FLT3-ITD in 40%. Favorable prognosis when found in isolation AML with biallelic mutations of CEBPA Blasts ≥20%. No distinctive morphological features, but most commonly AML with or without maturation. Less commonly monocytic or myelomonocytic CD13+, CD33+, CD65+, CD11b+, CD15+ HLA-DR ± and CD34± Aberrant CD7 in over 50% Abnormal karyotype in 30% FLT3-ITD in 22–33% cases Favorable prognosis. Provisional: AML with mutated RUNX1 Blasts ≥20% CD13+, CD33+, MPO+ Cases with MDS-related cytogenetic abnormalities excluded from this category Unfavorable prognosis AML with myelodysplasia-related changes AML with myelodysplasia-related changes Blasts ≥20%. Most cases have morphological evidence multilineage dysplasia. Morphological classification requires dysplasia in ≥50% cells in ≥2 lineages Other defining criteria are MDS-related cytogenetic abnormalities or a preceding diagnosis of MDS Variable findings CD34+, Tdt+, CD13+, CD33+ Aberrant CD7 and CD56 common Chromosome abnormalities are similar to those in MDS (Table 6) 10 year survival 16% Therapy-related myeloid neoplasms Therapy-related AML/MDS and AML/MDS/MPN Blasts ≥20% to diagnose AML. Often preceded by myelodysplastic phase. Multilineage dysplasia present in the majority. Distinguishing therapy-related AML, MDS and MDS/MPN may not be clinically relevant. Best considered as one clinical syndrome No specific immunophenotypic findings CD34+, CD33+, CD13+ Aberrant CD7 and CD56 common. Abnormal karyotype in >90%. Unbalanced aberrations in 70%, mainly loss of material from chromosome 5 and 7, associated with myelodysplastic phase (longer latency) In 20–30% balanced translocations are found and most often present as de novo AML (shorter latency) AML, not otherwise specified AML with minimal differentiation ≥20% blasts. No evidence of myeloid differentiation by light microscopy (absence of granulation and auer rods) CD34+, HLA-DR+, CD38+, CD13+ MPO- CD117±, CD33± Aberrant CD7 in 40% Complex karyotype most common abnormality. Unbalanced MDS-related abnormalities and RUNX1 mutations result in assignment to alternative categories AML without maturation ≥20% myeloid blasts. Blasts ≥90% of non-erythroid cells MPO+, CD13+, CD33+, CD117+ CD34+, HLA-DR+ Aberrant CD7 in 30% Aberrant CD2, CD4, CD19 or CD56 in 10–20% No association with specific recurrent chromosomal abnormalities AML with maturation ≥20% myeloid blasts ± azurophilic granules; ≥10% maturing cells of neutrophil lineage. Cells of monocytic lineage ≤20% of BM cells CD13+, CD33+, CD15+ CD34±, CD117±, HLA-DR± Aberrant CD7 in 20–30% No association with specific recurrent chromosomal abnormalities Acute myelomonocytic leukemia ≥20% myeloblasts, monoblasts, promonocytes; ≥20% monocytes and monocytic precursors; ≥20% neutrophils and granulocytic precursors Multiple blast populations CD13+, CD33+ Immature: CD34+, CD117+ Granulocytic: CD15+ Monocytic: CD14+, CD4+, CD11b+, CD11c + CD64+, CD36+ Aberrant CD7+ 30% Myeloid-associated, nonspecific cytogenetic abnormalities common e.g., trisomy 8 Acute monoblastic/monoctyic leukemia ≥80% monocytic cells; monoblastic if ≥80% are monoblasts or monocytic if <80% are monoblasts HLA-DR+, CD13+, CD33+, CD15+ ≥2 of CD14+, CD11b+, CD11c+, CD64+, CD36+ MPO−/+ more common in monocytic Aberrant CD7+/CD56+ 25–40% Myeloid associated, nonspecific cytogenetic abnormalities are present in the majority of cases Pure erythroid leukemia >80% immature erythroid precursors with ≥30% proerythroblasts CD117±, CD36+, CD235a (glycophorin A) −/+, MPO−, HLA-DR−, CD34−, CD41/61− No specific chromosomal abnormality, complex karyotype most common Unfavorable prognosis Acute megakaryoblastic leukemia ≥20% blasts with ≥50% shown to be of megakaryocyte lineage by immunophenotype CD36+, CD61+, CD41+, CD42 −/+ HLA-DR±, CD34±, CD45−/+, MPO- 3q26 abnormalities and t(1;22) result in assignment to alternative category Unfavorable prognosis Acute basophilic leukemia ≥20% blasts of basophilic lineage. Medium sized cells with oval to bilobed nucleus, nucleoli, basophilic cytoplasm and coarse basophilic granules CD13+, CD33+, CD123+, CD203+,CD11b, CD34±, HLA-DR±, CD117− Aberrant CD9+ in most No specific chromosomal abnormality Acute panmyelosis with myelofibrosis Pan myeloid proliferation with clusters of blasts. Dysplastic megakaryocytes. Marked reticulin fibrosis. Trephine diagnosis Blasts MPO−, CD13+, CD117+ Multilineage involvement – erythroid, megakaryocytic, granulocytic markers present Karyotype usually abnormal Myeloid proliferations related to Down syndrome Transient abnormal myelopoiesis (TAM) Unique disorder of Down syndrome newborns. Morphological features of acute megakaryoblastic leukemia. PB basophilia. Spontaneous remission in the majority. 20–30% develop nontransient AML 1–3 years later CD34+, CD56+, CD117+, CD13+, CD33+, CD7+, CD41+, CD42+, CD36+, CD61+ MPO−, CD15−, CD14− Trisomy 21 required and additionally acquired mutations in GATA1 are present Myeloid leukemia associated with Down syndrome Most commonly acute megakaryoblastic leukemia. No biological difference between MDS and AML therefore the term myeloid leukemia includes both morphological cases of MDS and AML CD34±, CD56±, CD117+, CD13+, CD33+, CD7+, CD41±, CD42+, CD36+, CD61+ MPO−, CD15−, CD14− Trisomy 21 required and additionally acquired mutations in GATA1 are present. Trisomy 8 common AML results in rapidly progressive bone marrow failure, hence the term “acute.” The replacement of normal hematopoiesis by proliferating myeloid blasts causes clinically significant, and often rapidly progressive, anemia, thrombocytopenia, and neutropenia. The resulting symptoms include fatigue, shortness of breath, bleeding, bruising, petechiae, pyrexia, and symptoms of infection. Disseminated intravascular coagulation can also be a presenting feature, most commonly in APL, and untreated can cause rapidly fatal bleeding. Central nervous system involvement at presentation occurs in approximately 0.5% of cases and can cause headaches and neurological symptoms or signs. The white cell count (WCC) is typically elevated, and if >150 × 109/L, symptoms of leucostasis which include headache, respiratory distress, and visual disturbance may be present. This is more common if the high WCC is comprised of monoblasts. Up to 10% of cases of AML may have an “aleukemic” presentation, with cytopenias and possible dysplastic features, but no blasts present in the peripheral blood. The majority of cases of AML occur with no known predisposing factors. However, in 10–15% of cases, prior treatment with chemotherapy or radiotherapy is implicated, and as increasing numbers of people survive their initial cancer, this is predicted to expand. AML can evolve from a prior acquired hematological condition, most often the myelodysplastic syndromes, but also myeloproliferative neoplasms. Rare environmental predisposing factors include exposure to benzene and ionizing radiation. Inherited conditions such as Down syndrome have long been known to greatly increase the risk of development of AML, particularly acute megakaryoblastic anemia. It was previously thought that the contribution of germline mutations to the development of AML was restricted to rare disorders such as Dyskeratosis Congenita and Fanconi anemia, or Bloom and Li-Fraumeni syndrome, which are characterized by defective DNA repair. However, it is increasingly recognized that up to 10% of people who develop AML have an inherited predisposition to hematological malignancies, and myeloid neoplasms with germline predisposition is a new entity in the most recent WHO classification (Table 2). The importance of a careful family history in patients with AML, and the involvement of geneticists to screen for potential germline alterations that may affect family members, is increasing. Incidence Table 2 Myeloid neoplasms with germline predisposition Myeloid neoplasm with germline predisposition without a pre-existing disorder or organ dysfunction Acute myeloid leukemia with germline CEBPA mutation Myeloid neoplasms with germline DDX41 mutation Myeloid neoplasms with germline predisposition and pre-existing platelet disorders Myeloid neoplasms with germline RUNX1 mutation Myeloid neoplasms with germline ANKRD26 mutation Myeloid neoplasms with germline ETV6 mutation Myeloid neoplasms with germline predisposition and other organ dysfunction Myeloid neoplasms with germline GATA2 mutation Myeloid neoplasms associated with bone marrow failure syndromes Myeloid neoplasms associated with telomere biology disorders Myeloid neoplasms associated with Noonan syndrome Myeloid neoplasms associated with Down syndrome Incidence The overall incidence of AML in the general population is 3/100,000. AML accounts for 90% of cases of acute leukemia in adults, but is rare in children, in whom acute lymphoblastic leukemia (ALL) predominates. Age Age The incidence of AML rises with age, from 1/100,000 at age 25 to over 15/100,000 by the age of 75. Due to the aging population, as well as increased survival post chemotherapy or radiotherapy for other cancers, the overall incidence of AML will rise over the coming decades. Sex Sex The sex ratio is 1:1 in younger people presenting with AML but there is a slight male preponderance in the over 65 s (ratio 1.3:1). The reason for this remains unclear. Treatment Treatment The backbone of treatment for AML remains cytotoxic chemotherapy; however, as the molecular basis of this disease is becoming more understood, novel targeted therapies are starting to improve survival in this disease. The mainstay of treatment for younger, fitter patients with AML is intensive induction chemotherapy consisting of an anthracycline (most often daunorubicin) and cytarabine (ELN guidelines 2017), followed by post-remission consolidation therapy. Molecularly targeted therapy, such as the FLT3 inhibitor midostaurin, or the anti-CD33 monoclonal antibody-drug conjugate gemtuzumab is now becoming increasingly used. Assessment of risk, based on genetic features, and the monitoring of minimal residual disease are critical to informing decisions regarding post remission treatment with additional cycles of intensive chemotherapy or high dose therapy followed by allogeneic transplant. The treatment of APL is significantly different to other forms of AML. Due to the coagulopathy that accompanies this form of AML, it used to be the subtype with the highest mortality. Since the 1980s, the PML-RARA fusion due to the t(15,17)(q22;q12) has been targetable directly with the vitamin A derivative all-trans retinoic acid (ATRA), which overcomes the differentiation block caused by this oncogene. ATRA may be used in combination with an anthracycline cytotoxic chemotherapy drug, resulting in complete remission rates of >90%. More recently, trials have demonstrated that an entirely chemotherapy-free treatment using ATRA with arsenic trioxide may be even more effective than the chemotherapy-containing regimes. Outcome Outcome Survival in AML is influenced primarily by age and the genetic abnormalities present. Overall, more than half of patients with AML will die from this disease. Increasing age adversely affects outcome for a number of reasons. These include inability to deliver intensive chemotherapy, higher treatment-related mortality, and higher rates of chemotherapy resistance. AML that is secondary to a prior hematological disorder such as MDS, or is therapy-related, have an adverse prognosis. The important role of genetics in risk stratification is highlighted by the European LeukemiaNet (ELN) guidelines, which have categorized genetic abnormalities into favorable, intermediate, and adverse (Table 3). Table 3 ELN 2017 risk stratification of AML by genetics Risk category Genetic abnormality Favorable t(8;21)(q22;22); RUNX1-RUNX1T1 inv(16)(p13q22) or t(16;16)(p13;q22); CBFB-MYH11 Mutated NPM1 without FLT3-ITD or with FLT3-ITDlow( Bialleleic mutated CEBPA Intermediate Mutated NPM1 and FLT3- ITDhigh Wild type NPM1 without FLT3-ITD or with FLT3-ITDlow (w/o adverse risk lesions) t(9;11)(p21;q23); MLLT3-KMT2A Cytogenetic abnormalities not classified as favorable or adverse Adverse t(6;9)(p23;q34); DEK-NUP214 t(v;11q23); KMT2A rearranged t(9;22)(q34;q11); BCR-ABL1 inv(3)(q21;q26) or t(3;3)(q21;q26); GATA2,MECOM(EVI1) −5 or del(5q); −7; −17/abn(17p) Complex karyotype, monosomal karyotype Wild type NPM1 and FLT3- ITDhigh Mutated RUNX1, Mutated ASXL1 Mutated TP53 Outcomes vary considerably between the groups: for example patients with APL, due to t(15,17) have a 73% 10-year survival, compared to a 3% 10 year survival in those with disruption of the gene MECOM due to alterations in chromosome 3. However, as these genetic alterations become therapeutic targets, their prognostic significance may change. The laboratory diagnosis of AML involves morphological and histological assessment of peripheral blood and bone marrow, in addition to molecular and cytogenetic analysis. Bone marrow is aspirated and biopsied most commonly from the posterior iliac crest. Liquid bone marrow can be spread immediately on slides to make a smear, which ideally contains particles at the end of trails. The slides are stained with Wright Giemsa or MGG (May-Grunwald Giemsa) stains. While examination of the bone marrow trephine biopsy is not essential to establish the diagnosis of AML in most instances, and should be avoided in severely coagulopathic patients due to the increased bleeding risk, it may contribute valuable information. At diagnosis, where there is significant marrow fibrosis, hypocellular samples or other reasons for an inadequate aspirate, the trephine is needed for diagnosis. The diagnosis of acute panmyelosis with fibrosis can only be made from a trephine, or increased fibrosis in addition to other histological features may suggest a preceeding myeloproliferative neoplasm. For follow-up samples post-chemotherapy, histological examination of the bone marrow can often best inform the treatment response and hence remission status. Ideally the bone marrow core should be 1.5–2.0 cm in length. In the case of a dry or aparticulate aspirate, the trephine can be rolled on a slide to produce a trephine roll, which can give a more rapid indication of an elevated blast count. If a poor liquid sample is obtained, then a trephine biopsy may be taken into saline, and disaggregated for immunophenotyping by flow cytometry. The DNA obtained from trephine samples taken into saline is usually better preserved than when DNA is extracted from formalin-fixed trephine biopsies. This may be used for molecular analysis if no liquid bone marrow is available, and where there are low numbers of blasts in the peripheral blood. The WHO classification has moved on from using morphology as the primary means for classification of AML. However, morphology is critical in identifying and enumerating blasts and in the identification of specific subgroups of AML. A myeloid blast count ≥20% in the peripheral blood or bone marrow is required for the diagnosis of AML, The exception to the requirement for >20% blasts is the presence of cytogenetic translocations t(8,21), inv(16), t(16,16), or t(15,17) which are categorized as AML provided >5% blasts are present. Blast morphology is best appreciated in the bone marrow aspirate sample and morphological features are detailed in Table 4 (Fig. 1a). Table 4 Blast morphology Myeloblasts Medium to large sized cells (14–18 μm) with a single round or oval nucleus Fine chromatin with one to several distinct nucleoli Minimal to moderate amount of basophilic cytoplasm Myeloid blasts are usually granular (minimally differentiated AMLs being one exception) Some contain Auer rods (fused granules in a rod-like form), which are pathognomic of AML Monoblasts Larger than myeloblasts (15–20 μm) Single round nucleus and visible nucleoli Voluminous blue-grey cytoplasm Often vacuolated Promonocytes Blast equivalent Appearances similar to monoblasts Lobulated nucleus with less prominent nucleoli and more prominent vacuolation Proerythroblasts Medium to round large cells with nucleoli Minimal deeply basophilic cytoplasm Cases with ≥80% immature erythroid precursors and ≥ 30% proerythroblasts are classified as pure erythroid leukemia under AML, NOS. Megakaryoblasts Medium to large cells (12–18 μm) Usually lack granules Cytoplasmic blebbing Open image in new window Fig. 1 Morphological features of AML (a) myeloblast in aspirate sample (b) the marrow is hypercellular with expansion of immature hemopoietic precursors expressing CD34 (c). (d) Faggot cell in a case of APL with an accumulation of Auer rods in its cytoplasm giving an appearance of a “bundle of sticks” (e) H&E appearances of APL in trephine biopsy. (f) Blast and dysplastic eosinophils in AML with inv(16)(p13q22) Immunocytochemistry is now rarely performed due to the universal use of flow cytometry. Historically, cytochemical stains such as Sudan black were used to confirm myeloid lineage. A toludine blue stain can be used to help confirm the diagnosis of the very rare acute basophilic leukemia, if this is suspected. In most cases, the bone marrow trephine biopsy is hypercellular with expanded myelopoiesis and virtual maturation arrest (Fig. 1b). Most of the cellularity is accounted for by CD34+ immature hemopoietic precursors with a high nuclear to cytoplasmic ratio (Fig. 1c). The other two lineages might be difficult to appreciate in the routine hematoxylin and eosin (H&E) stained sections and necessitate the use of immunohistochemistry, particularly when there is a suspicion of AML with myelodysplasia-related changes. Careful examination of bone marrow trephine sample is particularly useful in cases of hypocellular AML and ones with significant fibrosis as bone marrow aspirate in both instances may be nondiagnostic. APL is the most important subtype of AML to identify morphologically, as appropriate supportive care and ATRA must be started as soon as possible to reduce early mortality. A careful examination of the peripheral blood is essential, as APL often presents as a pancytopenia, and hence there may be limited numbers of leukocytes to assess. The atypical promyelocytes in the more common hypergranular variant are often packed with large cherry-red granules, and the nucleus is often bilobed. These are often called “dumbell,” “buttock,” or “butterfly” cells. Auer rods can be a prominent feature, and the term “faggot cell” is used to describe the pathognomonic promyelocytes containing large numbers of Auer rods that resemble bundles of sticks (Fig. 1d). The microgranular variant can be less easy to identify morphologically as the granules are submicroscopic. The clue to the diagnosis lies in the typical nuclear morphology, as in the hypergranular variant. Auer rods and more typical granular forms are often present in small numbers. The bone marrow trephine is hypercellular due to myeloid expansion (Fig. 1e). There is an accumulation of promyelocytes with abundant, often granular, cytoplasm and convoluted/bean shaped nucleli. AML with t(8,21)(q22;q22) typically has the morphological appearances of AML with maturation. Auer rods are more often present than in other subtypes of non-APL AML, these are usually present singly within myeloid blasts. In AML with inv(16)(p13q22) or t(16,16)(p13;q22), the peripheral blood often contains increased numbers of monocytes and promonocytes, with an often marked increase in eosinophils in the bone marrow (Fig. 1f). Dysplastic features are often seen in AML; however, dysplasia must be present in >50% of cells in ≥2 lineages to be classified morphologically as AML with myelodysplasia related changes (Fig. 2). In the bone marrow trephine, dyserythropoiesis is characterized by maturation synchrony within and dys-synchrony between erythroid islands. Dispersal of immature erythroid precursors and para-trabecular translocation are also often seen. Dysmegakaryopoiesis often manifests as decreased cell size and simplification of nuclear features. Forms are often small/hypolobated or micromegakaryocytes (Fig. 2). They might display dispersal of nuclear lobes. Open image in new window Fig. 2 AML with MDS-related changes. Blast are identifiable in the aspirate sample (a) as well as tissue sections (b) stained with CD34 (c). Dysplastic megakaryocytes show nuclear simplification and abnormal separation of nuclear lobes as seen in the aspirate (a), bone marrow trephine, H&E (b), and CD61 (d) stained sections This diagnosis can also be made if AML develops from a prior myelodysplastic syndrome, or in the presence of MDS-related cytogenetic abnormalities (Table 5). AML with mutated NPM1 or biallelic mutation of CEPBA are excluded from this category, even if significant dysplasia is present. They are categorized according to these mutations and the relatively favorable prognosis relating to them, compared to the adverse prognosis of AML with MDS-related changes. Table 5 Cytogenetic abnormalities sufficient to diagnose AML with MDS-related changes Cytogenetic abnormalites Complex karyotype (3 or more abnormalities) Unbalanced abnormalities Balanced abnormalities −7/del(7q) t(11;16)(q23;p13) del(5q)/t(5q) t(3;21)(q26;q22) i(17q)/t(17p) t(1;3)(p36;q21) −13/del(13q) t(2;11)(p21;q23) del(11q) t(5;12)(q32;p13) del(12p)/t(12p) t(5;7)(q32;q11) idic(X)(q13) t(5;17(q32;p13) t(5;10)(q32;q21) t(3;5)(q25;q35) Therapy-related myeloid neoplasms occur as a result of prior exposure to chemotherapy and/or radiotherapy. The most commonly implicated cytotoxic drugs are alkylating agents and topoisomerase II inhibitors. Alkylating agent and radiation induced AML usually occurs 5–10 years post therapy and is characterized by the MDS-related cytogenetic changes listed in Table 5. In contrast, topoisomerase II inhibitor induced AML has a shorter latency (1–5 years) and is characterized by balanced translocations, most commonly involving KMT2A. Therapy-related AML is most commonly morphologically myelomonocytic, with dysplastic features often present. This subgroup is reserved for cases without a defining genetic abnormality, dysplasia, or prior therapy (Fig. 3). The morphological definitions of each subtype are outlined in Table 4. Open image in new window Fig. 3 Acute myelomonocytic leukemia, NOS with (a) blast equivalent promonocytes in aspirate sample and an expansion of myeloid cells (b), some with indented nuclei and also expressing CD68/PGM1 (c) in the bone marrow Morphological examination is performed to assess response to chemotherapy, disease dynamics, and remission status. Depending on the timing of the sampling, the bone marrow is often hypocellular and displays variable ratios of hematopoietic cells lineages. The erythroid lineage is the first to recover post chemotherapy, followed by myeloid and megakaryocytic lineages. Dysplastic changes might be apparent, either due to the chemotherapy or persistence of an underlying MDS in AML with MDS-related changes. Assessment of blast percentage is often difficult in hypocellular cases due to suboptimal aspirate and flow cytometry samples. Immunohistochemistry is of particular importance in these cases. Often CD34 and CD117 are appropriate blast markers, but attention must be paid to the immunophenotype of the blasts at diagnosis, as either one or both of these markers may be negative at diagnosis. CD117 also highlights erythroid precursors which may be increased as the bone marrow recovers from chemotherapy. Repeat sampling may be required to distinguish between regenerating marrow and persistent disease, particularly where there is no leukemia-associated immunophenotype or genetic abnormalities, and the assessment of response is based on morphology alone. The marrow stroma is often edematous with mild increase in reticulin fibers and increased macrophage activity. Immunophenotyping using multi-color flow cytometry is central to establishing the diagnosis of AML. Standard panels of antigens that are informative in AML have been published in the ELN guideline 2017. These are detailed in Table 6. Different subtypes of AML have characteristic immunophenotypic profiles which can give an early indication of the disease category, although genetic assessment is always required. APL, for example, is typically CD9 positive, CD34, and HLA-DR negative, while AML with t(8,21) often aberrantly expresses the lymphoid antigen CD19. Flow cytometry will identify acute leukemias of ambiguous lineage. These may be acute undifferentiated leukemia, without adequate lineage-associated antigen expression to assign the leukemia to any lineage or mixed lymphoid/myeloid acute leukemia. The criteria for diagnosis of these rare mixed phenotype leukemias are stringent, as it is relatively common for AML blasts to aberrantly express lymphoid antigens. Table 6 Expression of cell surface and cytoplasmic markers for the diagnosis of AML Diagnosis of acute myeloid leukemia Markers of immaturity CD34, CD117, CD33, CD13, HLA-DR Granulocytic markers CD65, cytoplasmic myeloperoxidase (MPO) Monocytic markers CD14, CD36, CD64 Megakaryocytic markers CD41 (glycoprotein IIb/IIa), CD61 (glycoprotein IIIa) Erythroid markers CD234a (glycophorin A), CD36 The identification of cytogenetic and molecular abnormalities is now central to the classification of AML. The recurrent molecular features of interest can be broadly categorized into abnormalities visible at the chromosomal level and those visible only at the molecular genetic level. Genetic testing should be performed if full diagnostic, prognostic, and therapy-guiding information is required, which may not be the case in situations where patients are not fit for intensive, remission-induction chemotherapy. The exception is APL, which should almost always be confirmed genetically. Overall 60% of cases of AML have an abnormal karyotype. In children and younger adults, balanced translocations predominate, whereas in older adults unbalanced translocations as well as chromosomal losses and gains are more common. Over 100 balanced translocations have been recurrently associated with AML, although only 8 chromosomal abnormalities and their variants are at present included in the WHO classification. The majority of these translocations result in the formation of chimeric fusion proteins, which disrupt transcription factors involved in hematopoiesis. Chromosomal abnormalities can be visualized using Giemsa stained metaphase preparations to determine the karyotype. Cytogenetic analysis usually requires the examination of at least 20 metaphase cells and is best performed on a bone marrow aspirate sample taken into cytogenetic culture medium. The limitations of karyotyping include failure to obtain results due to metaphases failing to grow in culture, or failure to detect abnormalities due to the presence of small or cryptic chromosomal rearrangements (seen in up to 10% of those with canonical chimeric fusion genes). It is relatively labor intensive and takes a minimum of several days to obtain results. Fluorescence in situ hybridization (FISH) is used where rapid results are required (for example in suspected APL), or in cases where karyotyping fails. Specific FISH probes in routine use can detect PML-RARA, RUNX1-RUNX1T1, CBFB-MYH11, KMT2A fusions, BCR-ABL1, abnormalities of 3q26, complex karyotypes, and loss of TP53. Usually 100–200 interphase cells are assessed, although metaphase FISH can be used if interphase FISH is equivocal. The α and β subunits of the core binding factor (CBF) complex are affected by the t(8,21)(q22;22) and inv(16)(p13q22)/t(16,16)(p13;q22) translocations, which lead to the formation of chimeric fusion proteins RUNX1 (AML1/CBFα2)-RUNX1T1 (ETO) and CBFβ-MYH11, respectively. These translocations occur in approximately 13% of AML cases in younger adults and are associated with a more favorable prognosis. The initiating event in the vast majority of cases of APL is a chromosomal translocation juxtaposing PML (promyelocytic leukemia gene) with RARα (retinoic acid receptor alpha). The PML-RARα fusion protein causes enhanced recruitment of repressive complexes to chromatin. The PML-RARα complexes bind to many normal and novel RARα target genes and repress their expression by deacetylation and DNA/histone methylation. This enhanced repression is integral to the pathogenesis of APL and is reversed by treatment with ATRA (All-Trans Retinoic Acid). The combination of ATRA and arsenic trioxide is the first “non-chemotherapeutic” treatment regime for an acute leukaemia. The 3q26 translocations inv(3)(q21;q26) and t(3;3)(q21;26) are unusual in that they do not result in the formation of a fusion gene, but rather result in the repositioning of a distal GATA2 enhancer causing haploinsufficiency of GATA2 and activation of MECOM expression. These abnormalities confer an extremely adverse prognosis. The methyltransferase KMT2A which was previously called MLL has over 70 identified fusion gene partners to date. The most common of these are MLLT3 (AF9), MLLT1 (ENL), MLLT10 (AF10), MLLT4 (AF6), and ELL. These translocations confer a generally adverse prognosis, the exception being t(9;11)(p21;q23) MLLT3-KMT2A, which confers an intermediate prognosis. A complex karyotype in AML is defined as three or more unrelated chromosome abnormalities in the absence of one of the WHO category defining recurring translocations. Complex karyotypes, along with loss of either the whole of chromosome 5 or 7, or loss of the q arm of these chromosomes are common MDS-related abnormalies (see Table 5) which confer a poor prognosis. The molecular landscape of AML at the sub-chromosomal level has been increasingly well characterized over recent years. There are just over 20 commonly mutated genes in AML, which can be grouped into nine functional categories (Table 7). Analysis of the patterns of co-occurring mutations has identified 11 non-overlapping groups with distinct clinical phenotypes and prognostic features. In addition to the already recognized groupings in the WHO classification three new groupings have been postulated: AML with mutations in chromatin and RNA-splicing regulators, AML with TP53 mutations, and AML with IDH1 mutations. Table 7 Commonly mutated genes in AML Functional category Genes Transcription factor fusions PML-RARA, RUNX1-RUNX1T1, CBFB-MYH11 NPM1 gene NPM1 Tumor suppressor genes TP53, WT1, PHF6 DNA methylation related genes DNMT3A, TET2, IDH2, IDH1 Signaling genes FLT3, KIT, KRAS, NRAS, PTPN11 Chromatin modifying genes KMT2A (MLL) fusions, ASXL1, EZH2 Myeloid transcription factor genes RUNX1, CEBPA Cohesin complex genes SMC1A, SMC3, SMC5, RAD21 Spliceosome complex genes U2AF1, SF3B1 Molecular testing in AML should include NPM1, CEBPA, and RUNX1, which define disease categories, and FLT3 ITD/TKD and IDH1/2 as potentially targetable mutations with current therapies. In addition, mutations in several other genes such as in TP53, ASXL1, and WT1, provide further prognostic information. A variety of molecular sequencing techniques can be applied, but as information is required about increasing numbers of genes, large panel next-generation sequencing is increasingly taking the place of single gene tests. In the future whole exome or whole genome sequencing in AML will become increasingly used. Genetic alterations can be used to monitor minimal residual disease (i.e. 1 cell in a million) in follow up samples. FLT3 is a receptor tyrosine kinase expressed on hematopoietic progenitors and mutated in one third of AML cases. There are two main types of mutation that both result in the constitutive activation of the receptor. Internal tandem duplications (ITDs) occur in the juxta-membrane region of the receptor; less frequent are mutations in the tyrosine kinase domain (TKD). FLT3-ITD is an adverse prognostic indicator when present at high allelic ratios (resulting from acquired uniparental disomy), but both FLT3- mutations are now targetable by protein kinase inhibitors, improving overall survival. NPM1 is the most commonly mutated gene in AML, occurring in 35% of de novo cases of AML. NPM1 is a phosphoprotein which, whilst predominantly located in the nucleolus, constantly shuttles between the nucleus and the cytoplasm. A number of mutations have been described All result in loss of a nucleolar binding motif and commonly the gain of a nuclear export signal, leading to the aberrant cytosolic location of this protein. These mutations are not seen in the presence of balanced translocations but commonly co-occur with FLT3-ITD. NPM1 as a sole mutation confers a favorable prognosis. When co-occuring with high allelic FLT3 mutations, the prognosis of each combines to give an overall intermediate risk. CEBPA is mutated in 10% of AML cases. Mutations usually result in disruption of DNA binding/dimerations regions or the production of a truncated protein. Biallelic mutations are common, either resulting from uniparental disomy or acquisition, a second heterozygous mutation. Biallelic CEBPA mutations are generally associated with a favorable prognosis. In addition to the chromosomal translocation involving RUNX1-RUNX1T1, t(8;21), RUNX1 may also be mutated in AML and is included as a provisional entity in the 2016 WHO update. This confers an adverse prognosis. The main differential diagnosis for AML in a bone marrow aspirate or trephine is acute lymphoblastic leukemia, or an acute leukemia of ambiguous lineage. The morphology of lymphoblasts and myeloblasts can be very similar, particularly in the case of AML with minimal differentiation. Immunophenotyping or less commonly immunohistochemistry is required to confirm the diagnosis. Typically myeloblasts are larger than lymphoblasts and can possess a more irregular or convoluted nucleus and a lower nucleus:cytoplasmic ratio. Cytoplasmic granulation is a much more prominent feature of myeloblasts, but sparse granulation can occur in lymphoblasts. Auer rods are pathognomonic of AML. Other disorders that should be considered in the differential include high-grade lymphoma and blastic plasmacytoid dendritic cell neoplasm. Severe megaloblastic anemia should be excluded by checking B12 and folate, particularly before diagnosing pure erythroid leukemia. If blasts are increased but <20% and dysplasia is present, then myelodysplastic syndrome with excess blasts is the likely diagnosis. Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is an aggressive hematological malignancy derived from plasmacytoid dendritic cells (PDCs). In most patients, BPDCN presents with cutaneous lesions. These can be isolated nodules, isolated bruise-like plaques or present as disseminated nodules/papules/macules. Patients with leukemic presentation often lack skin lesions but display lymphadenopathy, splenomegaly, or signs and symptoms of bone marrow failure as in AML. Rare sites of involvement include the liver, tonsils, soft tissues, paranasal cavities, lungs, eyes, and central nervous system. While central nervous system involvement is seen 4 to 9% of patients at diagnosis, it is more frequent (17–33%) at relapse. Nearly 10%–20% of BPDCN patients either have a previous history of, or will develop another hematological malignancy, such as chronic myelomonocytic leukaemia (CMML), MDS, or AML. Incidence Incidence BPDCN is a very rare neoplasm and its exact incidence is unknown due to the low number of cases reported and no formal extensive studies. The largest study to date (379 cases) gives an incidence of 0.45/1,000,000. The variability of nomenclature further complicates assessment of the incidence. Age Age Most patients are elderly with a mean/median age of 61–67 years at diagnosis, although there are documented cases from all age groups, including children. Sex Sex About 75% of the patients are male with a male to female ratio of 2–5:1. Site Site Skin involvement is most common (64–100% of cases) with frequent bone marrow, peripheral blood (60–90%), and lymph node (40–50%) involvement. Treatment Treatment Treatment approach varies and best practice is not yet established. Surgical excision in combination with local radiotherapy and systemic steroid therapy has been assessed by a number of groups. While this might result in the resolution of the cutaneous lesion systemic relapse occurs within 6–9 months. Most conventional chemotherapy approaches consist of an AML or ALL-type acute leukemia-like treatment regimen. Intrathecal chemotherapy is often part of therapy as a pre-emptive measure in view of frequent leptomeningeal involvement. Allogeneic hematopoietic stem cell transplantation (HSCT), particularly when performed in first remission, may improve the survival. Outcome Outcome Disease outcome is poor with a clinical course similar to that of acute leukemia with high-risk features. The largest study to date of a cohort of 379 patients found a median overall survival of 23 months with an inferior survival rate of 19 months amongst patients receiving upfront HSCT as part of their treatment. Cutaneous lesions are often variable in size (few millimetres to over 10 centimentres) and purplish in color. They can be associated with erythema, hyperpigmentation, purpura, or ulceration. Histological examination of cutaneous lesions usually reveals a prominent dermal infiltrate, often extending onto the subcutaneous fat (Fig. 4a, b, and c). Epidermis and appendages are spared for the most part. Infiltrates within lymph nodes are mostly restricted to the paracortical areas and medulla with sparing of the cortex. The degree of bone marrow involvement (Fig. 4d and e) is highly variable. There may be features of associate hematological malignancies, such as myelodysplasia, most often identified by dysplastic features in the megakaryocyte lineage. Open image in new window Fig. 4 Blastic plasmacytoid dendritic cell neoplasm with cutaneous (a) and bone marrow (d) involvement. The neoplastic cells express CD123 (b – skin, e – bone marrow) and CD4 (c – skin). Cell morphology is best appreciated in the aspirate sample (f) The cellular morphology is best appreciated in aspirate (Fig. 4f) or peripheral blood samples. Blastic plasmacytoid dendritic cells are medium sized with a round or irregular nucleus with a fine or intermediate chromatin texture. They may have prominent nucleoli. They contain basophilic cytoplasm often forming a tail. The cytoplasm may contain small vacuoles under the cell membrane, which may give a monocytic appearance. BPDCs must be distinguished from acute leukemia or high-grade lymphoma by flow cytometry or immunohistochemistry, using combination antibodies targeting PDC-associated antigens such as CD123, CD303, and TCL1A. BPDCs also express CD45RA, CD4, CD56, and CD43, indeed they have previously been termed “CD4/CD56 positive cell tumors.” CD4 and CD56 are commonly included in panels assessing acute leukemias, and their dual positivity would lead to examination of the other PDC-associated antibodies that are not a standard component of most panels, even if this diagnosis had not previously been suspected by morphological assessment. Expression of other T-cell (CD7 and to a lesser extent CD2 and CD5 but not CD3), B cell associated (CD79a but not CD19 or CD20), as well as myeloid markers (CD33 and CD117 but not myeloperoxidase) are also frequent findings. About a third of the cases are positive for Tdt, and while CD34 is usually negative on tissue sections, it can often be detected by flow cytometry. CD68 shows cytoplasmic dot-positivity. Expression of BCL6, IRF4/MUM1, BCL2, and S100 can also be seen. Two-thirds of the cases harbor chromosomal abnormalities, often with a complex karyotype. The most frequently recurring, nonspecific chromosomal abnormalities involve 5q21 or 5q34, 12p13, 13q13–21, 6q23-qter, 15q, and loss of chromosome 9. The genomic landscape of BPDCNs is yet to be fully explored. Gene expression profiling has shown this neoplasm to be distinct from both myeloid and lymphoid malignancies and also revealed increased expression of genes involved with Notch signaling and activation of the NF-kappaB pathway, which may represent a promising therapeutic target. TET2 appears to be the most frequently mutated gene and recurrent mutations in ASXL1 and and RAS family genes have also been described. Mutations in genes recurrently mutated in AML, NPM1, FLT3-ITD, IDH2, TP53 and KIT have been detected in some patients. Recent studies have also described mutations in numerous other genes less commonly mutated in myeloid malignancies, such as BRAF, CDKN1B, CDKN2A. The main differential diagnoses of cutaneous lesions are cutaneous involvement by AML or benign mature plasmacytoid dendritic cell proliferations (MPDCP) accompanying myeloid neoplasia, particularly CMML. However, differentiating BPDCN from CD33+/CD4+/CD56+ AML, particularly if undifferentiated or myelomonocytoc/monoblastic with low-level CD123 expression, can be more challenging and usually relies on using additional BPDCN markers. Examination of a paired bone marrow sample is necessary with extensive flow cytometric and potentially molecular assessment, although from a clinical point of view, distinction might not be necessary for treatment planning. Distinction from neoplastic proliferation of mature plasmacytoid dendritic cells also requires bone marrow assessment. MPDCPs are often well-defined nodules of plasmacytoid dendritic cells with an immunophenotype of normal PDCs, although aberrant T-cell marker and/or myeloid marker (e.g., CD33) expression can also be seen. CD56 is usually negative or weakly positive and the proliferation index is low. Clonal genetic alterations shared with the associated myeloid malignancy can also be demonstrated.

To describe symptoms, diagnostic features, treatments, and outcomes of pneumatosis intestinalis (PI) in pediatric patients being treated for acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). This retrospective chart review included 514 patients ≤18 years of age diagnosed with ALL or AML between January 1999 and December 2007. PI episodes were identified by radiology report reviews. Twenty patients with ALL and four patients with AML presented 31 PI episodes. The median time between diagnoses of leukemia and PI was 1.0 month (interquartile range 0.8–6.4 months). Plain radiographs diagnosed all PI episodes. Computerized tomography (CT) and ultrasound were performed in 6 and 13 episodes, respectively. All CT and three ultrasounds demonstrated PI. Thirty episodes occurred exclusively in the colon, most commonly in the ascending (n = 26) and transverse (n = 18) segments. Treatment included complete bowel rest in 27 (87.1%) and intravenous broad-spectrum antibiotics in 29 (93.5%). One case required colectomy. Two episodes were untreated. There were no fatalities associated with PI. PI is uncommon in children with ALL or AML. Ultrasound is less sensitive than plain radiographs for diagnosis. PI occurred almost exclusively in the colon. With conservative management, most patients had excellent outcome.

Acute myeloid leukemia (AML) accounts for 15–20 % of the acute leukemias in children and 80 % of acute leukemia in adults [1, 2]. Significant advances as the result of multigroup cooperative trials have transformed this once uniformly fatal disease into one with a cure rate in children approaching 60 % [3], although the results are still significantly worse in adults. The difference in clinical outcome between childhood and adult AML is in part reflected by differences in the underlying biology. Recent advances in our understanding of stem cell physiology and the molecular basis of AML have elucidated the heterogeneity of AML and are leading to the identification of novel targets for therapy [4, 5]. The improvement in overall survival for children and young adults with AML can be attributed to better supportive care and advances in the application of chemotherapy and bone marrow transplantation. Future advancements in the treatment of children with AML will likely come about from the use of targeted therapies in conjunction with current chemotherapy regimens.

Children aged 0–2 years (i.e. infants) with acute myeloid leukemia (AML) are a peculiar subgroup of patients in the childhood AML scenario. They present with distinctive biological and clinical characteristics, including a high prevalence of prognostically unfavorable risk factors and an increased susceptibility to therapy-related toxicity. Remarkable improvements have been achieved over the last 2 decades in the treatment of these patients and their outcome is becoming superimposable to that of the older age groups. In this review, we will focus on peculiarities of this young subgroup of children with AML, describing their clinical presentation, the biology of disease and factors influencing outcome. Treatment results and toxicity data reported by major collaborative groups are also summarized and compared.

At the therapeutic intersection between children and older adults, the treatment of adolescent and young adults (AYAs) with acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) poses unique challenges due to their dismal outcome. In this brief review, we report on the biological features, clinical characteristics and treatment results of a pediatric and AYAs cohort of ALL and AML, treated in our department over a 15-year period. Additionally, we review the recent insights into disease biology, clinical, cytogenetic and molecular characteristics and differences between pediatric patients and AYAs with ALL and AML. In AYAs with ALL, most retrospective trials demonstrated a benefit of pediatric inspired regimens versus adult protocols. Translating the promising pediatric results to the AYAs subgroup, these patients can be successfully treated with risk-adjusted and minimal residual disease (MRD)-guided intensified chemotherapy, with survival rates that can surpass 70%. In AYAs the AML disease is genetically positioned more on the side of adult AML than on that of younger children, but also carries its own specific abnormalities, such as NUP98-NSD1. Toxicity may complicate all phases of treatment (induction and post-induction chemotherapy, hematopoietic stem cell transplantation-HSCT) and accounts for increased mortality, which counterbalances reduced cumulative incidence of relapse (CIR), in comparison with younger children. Intensification of supportive care while maintaining treatment intensity could further improve outcomes of AYAs with leukemia. Cooperative efforts between pediatric and adult hematologists are needed in order to further improve survival of AYAs with ALL and AML.

Objective: Leukemia is the most common pediatric malignancy and a major cause of morbidity and mortality in children. Among all subtypes, a lack of consensus exists regarding the diagnosis and treatment of acute myeloid leukemia (AML). Patient survival rates have remained modest for the past three decades in AML. Recently, targeted therapy has emerged as a promising treatment. Data Sources: We searched the PubMed database for recently published research papers on diagnostic development, target therapy, and other novel therapies of AML. Clinical trial information was obtained from ClinicalTrials.gov. For the major purpose of this review that is to outline the latest therapeutic development of AML, we only listed the ongoing clinical trials for reference. However, the published results of complete clinical trials were also mentioned. Study Selection: This article reviewed the latest developments related to the diagnosis and treatment of AML. In the first portion, we provided some novel insights on the molecular basis of AML, as well as provided an update on the classification of AML. In the second portion, we summarized the results of research on potential molecular therapeutic agents including monoclonal antibodies, tyrosine kinase/Fms-like tyrosine kinase 3 (FLT3) inhibitors, epigenetic/demethylating agents, and cellular therapeutic agents. We will also highlight ongoing research and clinical trials in pediatric AML. Results: We described clonal evolution and how it changes our view on leukemogenesis, treatment responses, and disease relapse. Pediatric-specific genomic mapping was discussed with a novel diagnostic method highlighted. In the later portion of this review, we summarized the researches on potential molecular therapeutic agents including monoclonal antibodies, tyrosine kinase/FLT3 inhibitors, epigenetic/demethylating agents, and cellular therapeutic agents. Conclusion: Gene sequencing techniques should set the basis for next-generation diagnostic methods of AML, and target therapy should be the focus of future clinical research in the exploration of therapeutic possibilities.

Acute myeloid leukemia (AML) is a heterogeneous group of diseases, whose classification is based on lineage-commitment and genetics. Although rare in childhood, it is the most common type of acute leukemia in adults, accounting for 80% of all cases in this age group. The prognosis of this disease remains poor (especially in childhood, as compared to acute lymphoblastic leukemia); however, overall survival has significantly improved over the past 30 years. The health of the oral cavity is a remarkable reflection of the systemic status of an individual. Identification of the signs and symptoms of oral lesions can act as a warning sign of hidden and serious systemic involvement. Moreover, they may be the presenting feature of acute leukemia and provide important diagnostic indicators. Primary oral alterations are identified in up to 90% of cases of acute myeloid leukemia and consist of petechiae, spontaneous bleeding, mucosal ulceration, gingival enlargement with or without necrosis, infections, hemorrhagic bullae on the tongue, and cracked lips. Poor oral hygiene is a well-known risk factor for local and systemic infectious complications. Oro-dental complications due to AML treatment can affect the teeth, oral mucosa, soft and bone tissue, and contribute to opportunistic infections, dental decay, and enamel discoloration. The treatment of acute myeloid leukemia is still associated with high mortality and morbidity. The management is multimodal, involving aggressive multidrug chemotherapy and, in most cases, allogenic bone marrow transplantation. Periodontal and dental treatment for patients with leukemia should always be planned and concerted with hematologists.

Acute myeloid leukemia (AML) accounts for only 15–20% of acute leukemias diagnosed in children. Pediatric and adult AML differ significantly in molecular characteristics and clinical features. These differences translate to overall better outcomes in children than adults. In the past 30 years, marked improvements in outcome have been achieved, especially for children with favorable AML subtypes. Progress is attributable to intensified treatment, optimized supportive care, and advances in stem cell transplantation. However, much more progress is needed to improve outcome and to decrease the burden of treatment for all patients.

Microbial infection is common in patients with leukemia. However, aspergillosis is a rare complication of oral region. Attention to early diagnosis and multidisciplinary treatment can reduce the wide range of complications of the infection in these patients. This article reports 4-year history of a child with leukemia, who suffered from a rare aspergillosis infection in the palatal region of oral cavity during chemotherapy. Early diagnosis and treatment of bacterial and fungal infections, especially rare types such as aspergillosis, in patients with leukemia is important for reducing widespread complications. However, prosthetic treatment and attention to psychological complications of orofacial defects would also improve their quality of life significantly. These improvements can be seen more clearly in children.

Concurrent presentation of acute promyelocytic leukemia (APL) with other hematologic diseases in the absence of previous chemotherapy or ionizing radiotherapy treatment is very rare. We present a case of simultaneous occurrence of APL with myelodysplastic syndrome (MDS)-related acute myeloid leukemia (AML). A 43-yearold female presented with 3 month of history fatigue, night sweats, chills and pancytopenia. Bone marrow aspirate and biopsy demonstrated 20% myeloid blasts with dysplastic changes admixed with abnormal promyelocytes. Cytogenetic analysis showed tetraploidy and deletion in chromosomes 5q and 7q and polymerase chain reaction showed presence of PML/RARA mRNA transcripts, confirming the presence of concurrent APL and MDS-related AML. Induction chemotherapy with cytarabine and daunorubicin was initiated along with all-trans retinoic acid. This is the first case to be reported in the literature of concurrent occurrence of APL with MDS-related AML. Treatment with 7 + 3 regimen and ATRA was successful in inducing complete remission.

Tristan Knight,1,2 Holly Edwards,3,4 Jeffrey W Taub,1–2,4 Yubin Ge2–41Division of Pediatric Hematology and Oncology, Department of Pediatrics, Children’s Hospital of Michigan, Detroit, MI, USA; 2Department of Pediatrics, Wayne State University School of Medicine, Detroit, MI, USA; 3Department of Oncology, Wayne State University School of Medicine, Detroit, MI, USA; 4Molecular Therapeutics Program, Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI, USAAbstract: Venetoclax (ABT-199), a BH3-mimetic and selective BCL-2 inhibitor, was recently approved by the US Food and Drug Administration (FDA) for the treatment of acute myeloid leukemia (AML) in adult patients aged 75 years or older, or otherwise unable to tolerate intensive induction chemotherapy, in combination with either hypomethylating agents or low-dose cytarabine. In this review article, we discuss venetoclax’s mechanism of action, in relation to both the BCL-2 protein family in general and BH3-mimetic activity in particular. We then outline the pharmacological advances that preceded and facilitated its development, as well as providing an overview of key preclinical and clinical studies which lead to its use first in chronic lymphoid leukemia (CLL), then in small lymphocytic leukemia (SLL), and subsequently in AML. Finally, we seek to offer an overview of the challenges and opportunities encountered as venetoclax moves into more widespread use, including its use and activity against leukemia initiating cells and oxidative phosphorylation.Keywords: ABT-199, acute myeloid leukemia, apoptosis, BCL-2 inhibitor, BH3-mimetic, venetoclax

The objectives of this review were to discuss standard and investigational treatment strategies for adolescent and young adult with acute myeloid leukemia, excluding acute promyelocytic leukemia. Acute myeloid leukemia (AML) in adolescent and young adult patients (AYAs) may need a different type of therapy than those currently used in children and older patients. As soon as AML is diagnosed, AYA patient should be offered to participate in well-designed clinical trials. The standard treatment approach for AYAs with AML is remission induction chemotherapy with an anthracycline/cytarabine combination, followed by either consolidation chemotherapy or stem cell transplantation, depending on the ability of the patient to tolerate intensive treatment and cytogenetic features. Presently, continuing progress of novel drugs targeting specific pathways in acute leukemia may bring AML treatment into a new era.

Background: Children with Down syndrome (DS) have increased risk for developing AML (DS-AMKL), and they usually experience severe therapy-related toxicities compared to non DS-AMKL. Refractory/ relapsed disease has very poor outcome, and patients would benefit from novel, less toxic, therapeutic strategies that overcome resistance. Relapse/resistance are linked to cancer stem cells with high aldehyde dehydrogenase (ALDH) activity. The purpose of the present work was to study less toxic alternative therapeutic agents for relapsed/refractory DS-AMKL. Methods: Fourteen AML cell lines including the DS-AMKL CMY and CMK from relapsed/refractory AML were used. Cytarabine (Ara-C), bortezomib (BTZ), disulfiram/copper (DSF/Cu2+) were evaluated for cytotoxicity, depletion of ALDH-positive cells, and resistance. BTZ-resistant CMY and CMK variants were generated by continuous BTZ treatment. Cell viability was assessed using CellTiter-Glo((R)), ALDH activity by ALDELUOR(TM), and proteasome inhibition by western blot of ubiquitinated proteins and the Proteasome-Glo(TM) Chymotrypsin-Like (CT-like) assay, apoptosis by Annexin V Fluos/Propidium iodide staining, and mutations were detected using PCR, cloning and sequencing. Results: Ara-C-resistant AML cell lines were sensitive to BTZ and DSF/Cu2+. The Ara-C-resistant DS-AMKL CMY cells had a high percentage of ALDHbright stem-like populations that may underlie Ara-C resistance. One percent of these cells were still resistant to BTZ but sensitive to DSF/Cu2+. To understand the mechanism of BTZ resistance, BTZ resistant (CMY-BR) and (CMK-BR) were generated. A novel mutation PSMB5 Q62P underlied BTZ resistance, and was associated with an overexpression of the beta 5 proteasome subunit. BTZ-resistance conferred increased resistance toAra-C due to G1 arrest in the CMY-BR cells, which protected the cells from S-phase damage by Ara-C. CMY-BR and CMK-BR cells were cross-resistant to CFZ and MG-132 but sensitive to DSF/Cu2+. In this setting, DSF/Cu2+ induced apoptosis and proteasome inhibition independent of CT-like activity inhibition. Conclusions: We provide evidence that DSF/Cu2+ overcomes Ara-C and BTZ resistance in cell lines from DS-AMKL patients. A novel mutation underlying BTZ resistance was detected that may identify BTZ-resistant patients, who may not benefit from treatment with CFZ or Ara-C, but may be responsive to DSF/Cu2+. Our findings support the clinical development of DSF/Cu2+ as a less toxic efficacious treatment approach in patients with relapsed/refractory DS-AMKL.

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The relapse rate for children with acute myeloid leukemia (AML) remains high despite advancements in risk classification, multi-agent chemotherapy intensification, stem cell transplantation, and supportive care guidelines. Prognosis for this subgroup of children with relapsed/refractory AML remains poor. It is well known that the ceiling of chemotherapy intensification has been reached, limited by acute and chronic toxicity, necessitating alternative treatment approaches. In the last several years, our improved understanding of disease biology and critical molecular pathways in AML has yielded a variety of new drugs to target these specific pathways. This review provides a summary of antibody drug conjugates (ADCs), small molecule inhibitors, and tyrosine kinase inhibitors with an emphasis on those that are currently under clinical evaluation or soon to open in early phase trials for children with relapsed/refractory AML.

Objective: To describe the epidemiological profile and the survival rate of patients with acute myeloid leukemia (AML) in a state reference pediatric hospital. Method: Clinical‐epidemiological, observational, retrospective, descriptive study. The study included new cases of patients with AML, diagnosed between 2004 and 2012, younger than 15 years. Results: Of the 51 patients studied, 84% were white; 45% were females and 55%, males. Regarding age, 8% were younger than 1 year, 47% were aged between 1 and 10 years, and 45% were older than 10 years. The main signs/symptoms were fever (41.1%), asthenia/lack of appetite (35.2%), and hemorrhagic manifestations (27.4%). The most affected extra‐medullary site was the central nervous system (14%). In 47% of patients, the white blood cell (WBC) count was below 10,000/mm3 at diagnosis. The minimal residual disease (MRD) was less than 0.1%, on the 15th day of treatment in 16% of the sample. Medullary relapse occurred in 14% of cases. When comparing the bone marrow MRD with the vital status, it was observed that 71.42% of the patients with type M3 AML were alive, as were 54.05% of those with non‐M3 AML. The death rate was 43% and the main proximate cause was septic shock (63.6%). Conclusions: In this study, the majority of patients were male, white, and older than 1 year. Most patients with WBC count < 10,000/mm3 at diagnosis lived. Overall survival was higher in patients with MRD < 0.1%. The prognosis was better in patients with AML‐M3.

Survival rates for children with acute myeloid leukemia (AML) exceed 60 % when modern, intensified chemotherapeutic regimens and enhanced supportive care measures are employed. Despite well-recognized improvements in outcomes, primary refractory or relapsed pediatric AML yields significant morbidity and mortality, and improved understanding of this obstinate population along with refined treatment protocols are urgently needed. Although a significant number of patients with refractory or relapsed disease will achieve remission, long-term survival rates remain poor, and efforts to identify therapies which will improve OS are under continuous investigation. The current fundamental goal of such investigation is the achievement of as complete a remission as possible without dose-limiting toxicities, and the progression to hematopoietic stem cell transplantation thereafter. In this review the scope of the problem of relapsed and refractory AML as well as current and emerging chemotherapy options will be discussed.

This article is from Contemporary Oncology, volume 18. Abstract Aim of the study: Recent studies showed relatively better outcome for children with refractory (refAML) and relapsed acute myeloid leukemia (relAML). Treatment of these patients has not been unified within Polish Pediatric Leukemia/Lymphoma Study Group (PPLLSG) so far. The goal of this study is to analyze the results of this therapy performed between 2005–2011. Material and methods: The outcome data of 16 patients with refAML and 62 with relAML were analyzed retrospectively. Reinduction was usually based on idarubicine, fludarabine and cytarabine with allogenic hematopoietic stem cell transplant (alloHSCT) in 5 refAML and 30 relAML children. Results: Seventy seven percent relAML patients entered second complete remission (CR2). Five-year OS and disease-free survival (DFS) were estimated at 16% and 30%. The outcome for patients after alloHSCT in CR2 (63%) was better than that of those not transplanted (36%) with 5-year OS of 34% vs. 2-year of 7% and 5-year DFS of 40% vs. 12.5%. Second complete remission achievement and alloHSCT were the most significant predictors of better prognosis (p = 0.000 and p = 0.024). The outcome of refAML children was significantly worse than relAML with first remission (CR1) rate of 33%, OS and DFS of 25% at 3 years and 53% at 2 years, respectively. All survivors of refAML were treated with alloHSCT after CR1. Conclusions: The uniform reinduction regimen of the documented efficacy and subsequent alloHSCT in remission is needed to improve the outcome for ref/relAML children treated within PPLLSG. The focus should be on the future risk-directed both front and second line AML therapy.

role=tabpanel class=tab-pane active> The association between 6-Thioguanine (6-TG) treatment and drug-induced liver injury has been reported since 1976. Recent reports have suggested that treatment of patients with 6-TG can lead to chronic hepatotoxicity and portal hypertension. Most of the cases reported to have 6-TG related hepatotoxicity had acute lymphoblastic leukemia or inflammatory bowel disease. In this case report, we discussed the diagnosis and approach in an acute myeloid leukemia patient who developed 6-TG related chronic hepatotoxicity. The Journal of Pediatric Research 2015;2(1):102-4

Since 1983 four consecutive unified regimens: acute myeloid leukemia-Polish pediatric leukemia/lymphoma study group (AML-PPLLSG) 83, AML-PPLLSG 94, AML-PPLLSG 98 and AML-BFM 2004 Interim, for AML have been conducted by the Polish Pediatric Leukemia/Lymphoma Study Group (PPLLSG). In this paper, we review four successive studies on the basis of acute myeloid leukemia-Berlin–Frankfurt–Munster (AML-BFM) protocol, in which a stepwise improvement of treatment outcome was observed. Treatment results of the last protocol AML-BFM 2004 Interim are presented in detail. Three hundred and three patients with de novo AML were treated according to the AML-BFM 2004 Interim at 15 Polish centers from January 1, 2005 to June 30, 2011. A confrontation with previous treatment periods was based upon historical, already published data. In four consecutive periods, 723 children were eligible for evaluation (208, 83, 195, and 237, respectively). Complete remission rates in consecutive periods were: 71, 68, 81 and 87 %, respectively. The 5-year overall survival rates, event-free survival rates, and relapse-free survival rates were 33, 32, and 45%, respectively for AML-PPLLSG 83 regimen; 38, 36, and 53 % respectively for AML-PPLLSG 94 regimen; 53, 46, and 65 % respectively for AML-PPLLSG 98 regimen, and 63, 52, and 64 % for AML–BFM Interim 2004, respectively. Incidence of early deaths and that due to complications (mainly infections) in the first remission decreased over time from 22 to 4.6 % and from 10 to 5.9 %, respectively. Despite continuous improvement in the treatment outcome, the number of failures still remains too high. Further progress seemed to be possible due to continued cooperation of oncology centers within large international study groups.

It is believed that there are key differences in the genomic profile between adult and childhood acute myeloid leukemia (AML). Relapse is the significant contributor of mortality in patients with AML and remains as the leading cause of cancer death among children, posing great challenges in the treatment of AML. The knowledge about the genomic lesions in childhood AML is still premature as most genomic events defined in children were derived from adult cohorts. However, the emerging technologies of next generation sequencing have narrowed the gap of knowledge in the biology of AML by the detection of gene mutations for each sub-type which have led to the improvement in terms of prognostication as well as the use of targeted therapies. In this review, we describe the recent understanding of the genomic landscape including the prevalence of mutation, prognostic impact, and targeted therapies that will provide an insight into the pathogenesis of AML relapse in both adult and childhood cases.

Thesis (M.A.)--Boston University PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / One third of all childhood cancer diagnoses are leukemias, making it is the most common cancer found in children. While overall survival for acute lymphoid leukemia (ALL) has improved greatly over the past 20 years, the survival rate for acute myeloid leukemia (AML) is still lagging behind. There are many biological classes of AML, several of which are largely resistant to intensive chemotherapy, necessitating the investigation of alternative treatment approaches. In particular, aberrant activation of the ERK signaling pathway has been associated with resistance to chemotherapy and decreased survival. The RAF kinases are central components of the ERK signaling pathway that are rarely mutated but often activated in AML. To understand the therapeutic potential of RAF kinase inhibition in AML, we investigated the susceptibility of AML cell lines to the novel pan-RAF kinase inhibitor AZ628. This work identified classes of RAF kinase inhibition sensitive and resistant cell lines, with the resistance associated with secretion of soluble factors that enhance AML cell growth and survival. This therapeutically relevant finding led to the development of a new approach for the analysis of secreted proteomes elaborated by AML cells, with the identification of candidate autocrine survival factors. This knowledge promises to lead to the identification of improved targets of therapy in order to improve the treatment of patients with AML.

Patients with acute myeloid leukemia (AML) and hyperleukocytosis, defined as an initial white blood cell (WBC) count of ≥ 100 × 109/L, are often treated with leukapheresis. In this study, we have reported our experience of treating AML without leukapheresis. Methods: From November 1, 1995, to May 31, 2012, there were 74 children (≤18 years old) with de novo AML other than acute promyelocytic leukemia. Seventeen patients had an initial WBC count ≥ 100 × 109/L. Prompt chemotherapy was started within hours whereas leukapheresis was not performed. Results: The median age of the 17 patients with hyperleukocytosis was 7.4 years (range: 0–16 years), and the median initial WBC count was 177 × 109/L (range: 117–635 × 109/L). The median time between admission and initiation of chemotherapy was 4.5 hours (range: 2–72 hours) in patients with hyperleukocytosis, whereas it was 13 hours (range: 2–120 hours) in those without hyperleukocytosis. Seven patients (7/17, 41%) had one or more early complications before or during the first 2 weeks of chemotherapy. Fifteen of the 16 patients who received prompt chemotherapy achieved complete remission (93.8%), comparable with those without hyperleukocytosis (98.2%; p = 0.33). Conclusion: Children with AML and hyperleukocytosis, treated with prompt chemotherapy without leukapheresis, had minimal early morbidities.