MLT GlobeHematology: WBC disorders & leukemias – page 7
145 Hematology MCQs on WBC disorders & leukemias with answers and explanations.
Atypical CML, BCR::ABL1-negative (renamed MDS/MPN with neutrophilia in WHO 5th), is classified as:
It shows neutrophilic leukocytosis with prominent dysgranulopoiesis and lacks BCR::ABL1, so it belongs to the MDS/MPN overlap group rather than with true CML.
In chronic-phase CML, the usual BCR::ABL1 fusion protein (major breakpoint) has a molecular weight of about:
The M-bcr breakpoint in CML gives p210. The minor breakpoint (p190) is typical of Ph-positive ALL, and p230 is associated with rare neutrophilic CML.
Over long follow-up, polycythemia vera most often progresses to which of these?
PV can evolve into a spent phase with marrow fibrosis more often than into AML. It does not transform to CML, which requires BCR::ABL1.
Which immunophenotype is typical of chronic lymphocytic leukemia?
CLL cells are B cells (CD19+) that co-express the T-cell marker CD5 and also CD23, with dim surface immunoglobulin. CD10 and TdT indicate B-lymphoblasts; CD11c, CD25 and CD103 indicate hairy cell leukemia.
Which peripheral blood finding most suggests a myelodysplastic syndrome?
MDS shows dysplasia; in neutrophils this is poor granulation and acquired bilobed nuclei (pseudo-Pelger-Huët). Hypersegmented neutrophils with macro-ovalocytes point to B12 or folate deficiency instead.
Medium-sized blasts with deep blue, vacuolated cytoplasm and a 'starry-sky' pattern on lymph node biopsy are associated with which translocation?
This is Burkitt lymphoma/leukemia, driven by MYC translocation, most often t(8;14) with IGH. t(14;18) is follicular lymphoma and t(11;14) is mantle cell lymphoma.
A 70-year-old has persistent WBC 40 × 10^9/L, over 80% segmented neutrophils and bands, no dysplasia, no BCR::ABL1, and a CSF3R T618I mutation. The most likely diagnosis is:
CSF3R mutation with sustained mature neutrophilia is characteristic of chronic neutrophilic leukemia. CML is excluded by absent BCR::ABL1 and lacks the typical basophilia and myelocyte peak.
A patient with marked eosinophilia and raised serum tryptase has a cryptic 4q12 deletion producing FIP1L1::PDGFRA. Why is this finding important?
FIP1L1::PDGFRA myeloid/lymphoid neoplasms with eosinophilia are highly sensitive to low-dose imatinib, which inhibits the PDGFRA kinase. It is a clonal, not reactive, process.
According to the WHO 5th edition, persistent monocytosis for a diagnosis of chronic myelomonocytic leukemia requires monocytes of at least:
WHO 5th lowered the absolute threshold to ≥0.5 × 10^9/L, with monocytes ≥10% of the WBC. The older threshold was 1.0 × 10^9/L.
Under the WHO 5th edition, which abnormality allows a diagnosis of AML even when blasts are below 20%?
WHO 5th removed the 20% blast requirement for AML with defining genetic abnormalities such as NPM1, except BCR::ABL1 and CEBPA types, which still need ≥20%. FLT3-ITD is not a defining abnormality.
For assigning myeloid lineage in mixed-phenotype acute leukemia, which marker is the most specific?
MPO (by flow or cytochemistry) is the key marker for myeloid lineage in MPAL. CD13, CD33 and CD117 can be expressed aberrantly in lymphoblastic leukemias.
A 4-month-old infant has B-ALL with WBC 250 × 10^9/L, CD10-negative blasts and t(4;11)(q21;q23). This finding indicates:
t(4;11) gives KMT2A::AFF1, common in infant ALL; blasts are usually CD10-negative and the outlook is poor. ETV6::RUNX1 and hyperdiploidy are favorable in older children.
In a patient with a plasma cell clone but no CRAB features, which finding alone is a myeloma-defining event?
IMWG biomarkers (SLiM): >=60% clonal marrow plasma cells, involved/uninvolved FLC ratio >=100 (involved FLC >=100 mg/L), or >1 focal lesion on MRI. 15% plasma cells or serum M-protein >=30 g/L define smoldering myeloma, and a urine M-protein of 300 mg/24 h meets neither smoldering (>=500 mg/24 h) nor myeloma criteria.
A CML patient responding well to imatinib shows rising BCR::ABL1 levels. Kinase domain sequencing finds T315I. What does this mean?
The T315I 'gatekeeper' mutation blocks binding of imatinib, dasatinib, nilotinib and bosutinib; ponatinib or asciminib are options. A higher imatinib dose does not overcome this mutation.
In Philadelphia-positive B-lymphoblastic leukemia of childhood, the BCR::ABL1 fusion most often produces a protein of about:
Most Ph-positive ALL (especially in children) has a break in the minor bcr region, giving the p190 (e1a2) protein. p210 is typical of CML; p230 is linked to a neutrophilic CML-like picture.
A CLL patient with WBC 300 × 10^9/L has serum potassium 7.2 mmol/L, a normal ECG and no symptoms. Heparinized plasma potassium measured promptly is 4.1 mmol/L. The best explanation is:
Fragile leukemic cells release potassium when blood clots, falsely raising serum potassium; a gently handled plasma sample shows the true value. Tumor lysis would raise potassium in both sample types.
An older man has marked splenomegaly and lymphocytes with short hair-like projections at one pole of the cell. Cells are CD19+, CD5−, CD103−, CD25−. The most likely diagnosis is:
'Villous' lymphocytes with polar projections and a CD5−/CD103− B-cell phenotype fit splenic marginal zone lymphoma. Classic hairy cell leukemia has circumferential projections and is CD103+, CD25+, CD11c+.
Circulating Sézary cells in a patient with erythroderma typically show which immunophenotype?
Sézary cells are mature helper T cells (CD4+) that commonly lose CD7 and CD26, which helps count them by flow cytometry. CD8+/CD57+ fits T-cell large granular lymphocytic leukemia.
A lymph node biopsy shows scattered large 'popcorn' cells that are CD20+, CD45+, CD15− and CD30−, in a background of small lymphocytes. The diagnosis is:
LP ('popcorn') cells keep a B-cell program (CD20+, CD45+) and lack CD15 and CD30, which defines nodular lymphocyte-predominant Hodgkin lymphoma. Classic Hodgkin cells are CD15+/CD30+ and usually CD20−.
Flow cytometry of blasts from a patient with DIC shows CD33 bright, CD13+, CD117+, HLA-DR negative and CD34 negative. This pattern suggests:
Leukemic promyelocytes are typically CD34− and HLA-DR−, with bright CD33. Most other AML types express HLA-DR, and monocytic blasts show CD14/CD64 with HLA-DR.