Myeloid neoplasms: acute myeloid leukemia

13 ASCP MLS practice questions on Myeloid neoplasms: acute myeloid leukemia, part of Hematology. The first 13 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Hard
A 34-year-old man was treated 2 years ago with bleomycin, etoposide and cisplatin for a testicular germ cell tumor and remains in remission. He now has gum swelling and tiredness; his blood count was normal 3 months ago. Results: WBC 74.0 × 10^3/µL [74.0 × 10^9/L] with 68% monoblasts and promonocytes, Hb 8.6 g/dL [86 g/L] and platelets 38 × 10^3/µL [38 × 10^9/L]. The blasts are strongly positive for nonspecific esterase, which sodium fluoride inhibits, and weak for myeloperoxidase. Flow cytometry: CD33+, CD64+, CD11b+, CD14 partial, CD4 dim and HLA-DR+. The karyotype shows t(9;11)(p21.3;q23.3), KMT2A::MLLT3. Which drug most likely caused this leukemia?
1. ACisplatin
2. BEtoposide
3. CBleomycin
4. DNone; this is de novo AML
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Answer: B · Etoposide
Monocytic AML (fluoride-sensitive nonspecific esterase, CD64, CD11b and CD14) with a KMT2A rearrangement, appearing about 2 years after treatment without a preceding myelodysplastic phase, is the typical picture of leukemia after a topoisomerase II inhibitor. Etoposide traps topoisomerase II on DNA and causes double-strand breaks, which can join KMT2A on 11q23 to partner genes such as MLLT3 on 9p. Under the WHO 5th edition this is reported as AML with KMT2A rearrangement, post cytotoxic therapy. Leukemias after alkylating-type drugs, a group that includes platinum agents, usually appear later, often after an MDS phase, with loss of chromosome 5 or 7 or a complex karyotype. Bleomycin is not an important cause of leukemia, and the treatment history means the AML cannot simply be called de novo.
- A: Alkylating-type leukemias come later, often after an MDS phase, with loss of 5 or 7 rather than a KMT2A fusion.
- C: Bleomycin is not an important cause of leukemia.
- D: The prior etoposide, the 2-year interval and the KMT2A fusion point to a therapy-related AML.
Question 2 · Medium
In a new acute leukemia, most leukemic cells stain diffusely for nonspecific esterase (alpha-naphthyl butyrate), sodium fluoride inhibits the stain, and MPO is weak or negative. Which diagnosis fits best?
1. AB-lymphoblastic leukemia
2. BAcute monocytic leukemia
3. CAcute promyelocytic leukemia
4. DAML with maturation
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Answer: B · Acute monocytic leukemia
Monocytic cells contain a nonspecific esterase that splits alpha-naphthyl butyrate and acetate, giving diffuse staining that sodium fluoride inhibits. Granulocytic cells instead stain with specific (naphthol AS-D chloroacetate) esterase and are strongly MPO positive. Monoblasts are often MPO negative, so the esterase stain is the key to recognizing monocytic leukemia. Acute monocytic leukemia often infiltrates the gums and skin.
- A: Lymphoblasts are MPO negative and lack diffuse fluoride-sensitive esterase.
- C: Promyelocytes in APL are intensely MPO positive.
- D: AML with maturation is strongly MPO positive and stains with specific, not nonspecific, esterase.
Question 3 · Hard
A 2-year-old with Down syndrome has anemia and thrombocytopenia. The marrow aspirate is a dry tap and the biopsy shows fibrosis. Blood blasts have cytoplasmic blebs and are MPO negative. Which markers would best confirm their lineage?
1. ACD19 and CD79a
2. BCD41 and CD61
3. CGlycophorin A and CD71
4. DCD14 and CD64
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Answer: B · CD41 and CD61
Acute megakaryoblastic leukemia is far more common in young children with Down syndrome, where WHO calls it myeloid leukemia associated with Down syndrome; it carries GATA1 mutations. Megakaryoblasts are MPO and Sudan black B negative, often have cytoplasmic blebs, and marrow fibrosis often causes a dry tap. Flow cytometry for the platelet glycoproteins CD41 (GPIIb) and CD61 (GPIIIa) confirms the lineage. Platelets stuck to blasts can give false CD41 positivity, so gating must be checked.
- A: CD19 and CD79a identify B-lineage cells.
- C: Glycophorin A and CD71 identify erythroid precursors.
- D: CD14 and CD64 identify monocytic cells.
Question 4 · Easy
What are Auer rods made of?
1. ADenatured hemoglobin
2. BFused primary granules
3. CNuclear chromatin fragments
4. DRibosomal RNA aggregates
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Answer: B · Fused primary granules
Auer rods are pink-red, needle-shaped inclusions formed when primary (azurophilic) granules fuse. Because they contain myeloperoxidase, they stain with MPO and Sudan black B. Finding them in blasts proves myeloid lineage. They are never seen in lymphoblasts.
- A: Denatured hemoglobin forms Heinz bodies in red cells.
- C: Nuclear chromatin fragments in red cells are Howell-Jolly bodies.
- D: Aggregated ribosomal RNA gives basophilic stippling in red cells.
Question 5 · Easy
In the WHO classification, AML defined by differentiation (no defining genetic abnormality) needs a blast count in blood or marrow of at least:
1. A10%
2. B30%
3. C20%
4. D5%
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Answer: C · 20%
AML without a defining genetic abnormality requires at least 20% blasts, including blast equivalents such as promonocytes, in the blood or marrow. Below this, a dysplastic marrow with excess blasts is classed as a myelodysplastic neoplasm. The older FAB scheme used 30%, which is why some older texts differ. In WHO 5th edition, most AML types with a defining genetic abnormality, such as PML::RARA, need no minimum blast count.
- A: 10% to 19% marrow blasts falls in MDS with increased blasts-2.
- B: 30% was the old FAB threshold, replaced by 20%.
- D: 5% is the upper limit of blasts in a normal marrow.
Question 6 · Medium
AML with inv(16) or t(16;16), CBFB::MYH11, characteristically shows which marrow finding?
1. APromyelocytes with bundles of Auer rods
2. BAbnormal eosinophils with large dark granules
3. CRing sideroblasts in erythroid precursors
4. DSmall hypolobated megakaryocytes
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Question 7 · Hard
A 34-year-old has gum bleeding. WBC 1.6 × 10^3/µL [1.6 × 10^9/L], platelets 21 × 10^3/µL [21 × 10^9/L], fibrinogen 70 mg/dL [0.7 g/L] (reference 200-400 mg/dL) and a high D-dimer. The marrow is packed with hypergranular promyelocytes. Which flow cytometry profile is expected?
1. ACD19+, CD10+, CD34+, TdT+
2. BCD33+, CD117+, CD34+, HLA-DR+
3. CCD14+, CD64+, CD34−, HLA-DR+
4. DCD33+, CD117+, CD34−, HLA-DR−
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Question 8 · Hard
A 74-year-old with no prior chemotherapy or radiation has pancytopenia. The marrow has 28% myeloblasts with dysplasia in all three lines, and the karyotype shows monosomy 7. Under WHO 5th edition, the best classification is:
1. AAML, myelodysplasia-related
2. BAML with maturation
3. CTherapy-related myeloid neoplasm
4. DMDS with increased blasts-2
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Question 9 · Hard
A marrow differential shows myeloblasts 20%, monoblasts and promonocytes 18%, promyelocytes to neutrophils 25%, mature monocytes 22%, other cells 15%. Double esterase staining shows separate chloroacetate-positive and butyrate-positive cells. Which diagnosis fits best?
1. AChronic myelomonocytic leukemia
2. BAML with maturation
3. CAcute myelomonocytic leukemia
4. DAcute monocytic leukemia
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Question 10 · Medium
AML with maturation, a single long slender Auer rod in many blasts, salmon-colored granules and a favorable prognosis is typical of:
1. At(8;21) RUNX1::RUNX1T1
2. Bt(9;11) KMT2A::MLLT3
3. Cinv(3) GATA2;MECOM
4. Dt(15;17) PML::RARA
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Question 11 · Medium
Why does all-trans retinoic acid (ATRA) work in acute promyelocytic leukemia?
1. AIt kills dividing blasts by blocking DNA
2. BIt inhibits the BCR::ABL1 tyrosine kinase
3. CIt replaces the fibrinogen consumed in DIC
4. DIt lets the blocked promyelocytes mature fully
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Question 12 · Hard
A patient with acute leukemia has many abnormal promyelocytes with bundles of Auer rods and develops DIC. Which genetic change is expected?
1. At(15;17) PML::RARA
2. Binv(16)
3. Ct(9;22) BCR::ABL1
4. Dt(8;14) involving MYC
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Question 13 · Medium
Auer rods in blast cells are characteristic of which leukemia?
1. AAcute myeloid leukemia
2. BAcute lymphoblastic leukemia
3. CHairy cell leukemia
4. DChronic lymphocytic leukemia
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Myeloid neoplasms: acute myeloid leukemia

In a new acute leukemia, most leukemic cells stain diffusely for nonspecific esterase (alpha-naphthyl butyrate), sodium fluoride inhibits the stain, and MPO is weak or negative. Which diagnosis fits best?

A 2-year-old with Down syndrome has anemia and thrombocytopenia. The marrow aspirate is a dry tap and the biopsy shows fibrosis. Blood blasts have cytoplasmic blebs and are MPO negative. Which markers would best confirm their lineage?

What are Auer rods made of?

In the WHO classification, AML defined by differentiation (no defining genetic abnormality) needs a blast count in blood or marrow of at least:

AML with inv(16) or t(16;16), CBFB::MYH11, characteristically shows which marrow finding?

A 34-year-old has gum bleeding. WBC 1.6 × 10^3/µL [1.6 × 10^9/L], platelets 21 × 10^3/µL [21 × 10^9/L], fibrinogen 70 mg/dL [0.7 g/L] (reference 200-400 mg/dL) and a high D-dimer. The marrow is packed with hypergranular promyelocytes. Which flow cytometry profile is expected?

A 74-year-old with no prior chemotherapy or radiation has pancytopenia. The marrow has 28% myeloblasts with dysplasia in all three lines, and the karyotype shows monosomy 7. Under WHO 5th edition, the best classification is:

A marrow differential shows myeloblasts 20%, monoblasts and promonocytes 18%, promyelocytes to neutrophils 25%, mature monocytes 22%, other cells 15%. Double esterase staining shows separate chloroacetate-positive and butyrate-positive cells. Which diagnosis fits best?

AML with maturation, a single long slender Auer rod in many blasts, salmon-colored granules and a favorable prognosis is typical of:

Why does all-trans retinoic acid (ATRA) work in acute promyelocytic leukemia?

A patient with acute leukemia has many abnormal promyelocytes with bundles of Auer rods and develops DIC. Which genetic change is expected?

Auer rods in blast cells are characteristic of which leukemia?