Myeloid neoplasms: myelodysplastic syndromes

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

1. Question 1 · Easy

   To call a cell line dysplastic in MDS, at least what proportion of that line's cells must show dysplasia?

   1. A5%
   2. B10%
   3. C20%
   4. D50%

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   Answer: B · 10%

   WHO sets the threshold at 10% of the cells of a lineage, for example 10% of erythroid precursors or of neutrophils. Below this, minor dysplastic changes can be seen in healthy people and in reactive states. Dysplasia must be judged on well-made, well-stained films, since poor technique can mimic it. Causes such as B12 or folate deficiency, alcohol, drugs and HIV must be excluded.

   • A: 5% is too low; minor changes at this level occur in normal marrows.
   • C: 20% is the blast threshold for AML, not the dysplasia threshold.
   • D: 50% is not a WHO criterion.

2. Question 2 · Medium

   A 70-year-old woman has macrocytic anemia and platelets of 520 × 10^3/µL [520 × 10^9/L]. Her marrow shows small megakaryocytes with round, non-lobed nuclei and 2% blasts. The expected cytogenetic finding is:

   1. ATrisomy 8
   2. BIsolated del(5q)
   3. CMonosomy 7
   4. DIsolated del(20q)

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   Answer: B · Isolated del(5q)

   This is MDS with low blasts and isolated 5q deletion (MDS-5q). It typically affects older women and shows macrocytic anemia, a normal or raised platelet count, and megakaryocytes with non-lobed or hypolobated nuclei. Blasts must be below 5% in the marrow and below 2% in the blood. Lenalidomide works very well in this subtype, so the karyotype directly guides treatment.

   • A: Trisomy 8 is common in MDS but has no specific blood picture.
   • C: Monosomy 7 is a poor-risk change without this platelet and megakaryocyte picture.
   • D: Isolated del(20q) is a nonspecific change in MDS and other myeloid neoplasms.

3. Question 3 · Hard

   A 69-year-old has anemia and erythroid dysplasia. Erythroid precursors are 60% of marrow nucleated cells, with few proerythroblasts. Myeloblasts are 9% of all nucleated cells (22% of non-erythroid cells). Blood blasts are 1%, the karyotype is normal and TP53 is not mutated. Under WHO 5th edition, the diagnosis is:

   1. AMDS with increased blasts-2
   2. BAcute erythroid leukemia
   3. CAcute myeloid leukemia
   4. DMDS with increased blasts-1

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   Answer: D · MDS with increased blasts-1

   Since the 2016 WHO revision, blasts are counted as a percentage of all nucleated marrow cells, even when erythroid cells are increased. Here that is 9%, which falls in MDS with increased blasts-1 (5% to 9% in the marrow or 2% to 4% in the blood). Using the non-erythroid count (22%) would wrongly suggest AML, as older classifications did. Acute erythroid leukemia needs 80% or more erythroid precursors with 30% or more proerythroblasts.

   • A: MDS with increased blasts-2 needs 10% to 19% marrow blasts or 5% to 19% blood blasts.
   • B: Acute erythroid leukemia needs at least 80% erythroid cells and 30% proerythroblasts.
   • C: AML needs 20% blasts among all nucleated cells, not among non-erythroid cells.

4. Question 4 · Medium

   In MDS with low blasts, ring sideroblasts make up 25% of erythroid precursors on an iron stain. Which gene is most likely mutated?

   1. ATP53
   2. BNPM1
   3. CSF3B1
   4. DFLT3

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   Answer: C · SF3B1

   Ring sideroblasts are erythroid precursors whose iron-laden mitochondria encircle at least a third of the nucleus on Prussian blue staining. Most MDS cases with 15% or more ring sideroblasts carry a mutation in the splicing factor gene SF3B1. WHO 5th edition names this subtype MDS with low blasts and SF3B1 mutation, and it has a relatively favorable prognosis. Ring sideroblasts are counted as a percentage of erythroid precursors, not of all marrow cells.

   • A: TP53 mutations go with complex karyotypes and a poor prognosis, not with ring sideroblasts.
   • B: NPM1 mutations are typical of AML with a normal karyotype.
   • D: FLT3 mutations are found mainly in AML.

5. Question 5 · Easy

   A classic sign of dysgranulopoiesis in a myelodysplastic syndrome is:

   1. AHypogranular neutrophils with bilobed nuclei
   2. BNeutrophils containing bacteria
   3. CA left shift with many bands
   4. DNeutrophils with toxic granulation

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   Answer: A · Hypogranular neutrophils with bilobed nuclei

   Dysplastic neutrophils in MDS are often hypogranular and have hypolobated nuclei, such as bilobed pseudo-Pelger-Huët forms. These changes reflect abnormal maturation of the neoplastic clone. Toxic granulation and a left shift point instead to infection or inflammation. Inherited Pelger-Huët anomaly and some drugs, such as mycophenolate, can mimic these changes, so the history matters.

   • B: Bacteria inside neutrophils indicate sepsis, not dysplasia.
   • C: A left shift with bands is a reactive response to infection.
   • D: Toxic granulation is a reactive change in infection and inflammation.