MLT GlobeHematology: WBC disorders & leukemias – page 5
145 Hematology MCQs on WBC disorders & leukemias with answers and explanations.
Which marker is considered most specific for T-lineage in acute lymphoblastic leukemia?
Cytoplasmic CD3 is the lineage-defining T-cell marker. CD7 is sensitive but also appears on some myeloid blasts.
The most common structural rearrangement in childhood B-ALL is often missed by routine karyotyping and has a favorable prognosis. It is:
ETV6::RUNX1 is cryptic on karyotype and needs FISH or PCR for detection; it carries a good outlook. BCR::ABL1 is uncommon in children and adverse.
A 65-year-old man has lymphocytosis and splenomegaly. Cells are CD19+, CD5+, CD23-negative, FMC7-positive and show bright surface light chain. Which test best confirms the likely diagnosis?
CD5+ CD23– B cells suggest mantle cell lymphoma, confirmed by cyclin D1 overexpression or t(11;14) CCND1::IGH. CLL is CD5+ but CD23+.
Which pair of findings best supports classic hairy cell leukemia rather than its variant?
Classic HCL is CD11c+, CD25+, CD103+, annexin A1+ and nearly always carries BRAF V600E. The variant lacks CD25 and BRAF V600E.
Flow cytometry of marrow from a myeloma patient would most likely show clonal plasma cells with which pattern?
Neoplastic plasma cells usually lose CD19 and aberrantly express CD56. Normal plasma cells are CD19+ and CD56-negative.
A 62-year-old has serum M-protein 15 g/L (1.5 g/dL), 6% clonal marrow plasma cells, and normal calcium, creatinine, Hb and bones. The best classification is:
MGUS: M-protein <30 g/L, clonal plasma cells <10% and no myeloma-defining events. Smoldering myeloma needs ≥30 g/L M-protein or 10–59% clonal plasma cells.
A man with blurred vision, headaches and nose bleeds has an IgM monoclonal protein and lymphoplasmacytic marrow infiltrate. Which mutation is found in over 90% of such cases?
Waldenström macroglobulinemia (lymphoplasmacytic lymphoma with IgM) carries MYD88 L265P in most cases; IgM causes hyperviscosity. BRAF V600E is typical of hairy cell leukemia.
In the WHO 5th edition, chronic myeloid leukemia is diagnosed as being in blast phase when blasts in blood or marrow reach at least:
Blast phase of CML is defined by ≥20% blasts in blood or marrow, an extramedullary blast proliferation, or increased lymphoblasts. The 10% level was used for the old accelerated phase, which WHO 5th edition no longer requires.
A 5-year-old with B-ALL has a blast karyotype of 55 chromosomes with extra copies of chromosomes 4, 10 and 21. This finding is:
High hyperdiploidy (51–65 chromosomes), often with gains of 4, 10 and 21, is one of the most common and most favorable cytogenetic groups in childhood B-ALL. Hypodiploidy (<44 chromosomes) is the unfavorable group.
Two days after induction chemotherapy for a high-count leukemia, which set of results suggests tumor lysis syndrome?
Rapid lysis of tumor cells releases potassium, phosphate and nucleic acids (converted to uric acid). Phosphate binds calcium, so calcium falls. The opposite pattern does not fit cell breakdown.
A glucose sample from a patient with WBC 250 × 10^9/L sat unseparated for 3 hours and reads 1.8 mmol/L (32 mg/dL). The patient has no symptoms. Likely cause:
Very high numbers of metabolically active cells keep using glucose after collection, giving a falsely low result. Rapid separation or a fluoride tube reduces this. Fluoride blocks glycolysis, so it would protect glucose, not lower it.
In chronic lymphocytic leukemia, which FISH result as the only abnormality predicts the most favorable course?
Isolated del(13q14) is the most common CLL abnormality and is linked to the best outcome. del(17p) (TP53 loss) is the worst, and del(11q) (ATM) is also unfavorable; trisomy 12 is intermediate.
Before therapy for chronic lymphocytic leukemia, testing for TP53 abnormality is important mainly because it:
del(17p)/TP53 mutation predicts resistance to standard chemoimmunotherapy, so these patients receive targeted agents such as BTK or BCL2 inhibitors. It is prognostic and predictive, not diagnostic.
A 70-year-old has a normal WBC, no lymphadenopathy, and 2.1 × 10^9/L monoclonal B cells with a CLL-type phenotype. The best classification is:
Clonal B cells below 5 × 10^9/L without lymphadenopathy, organomegaly or cytopenias define monoclonal B-cell lymphocytosis. CLL requires at least 5 × 10^9/L clonal B cells in blood.
A 60-year-old with rheumatoid arthritis has persistent neutropenia and increased large granular lymphocytes that are CD3+, CD8+, CD57+ with clonal TCR rearrangement. The likely diagnosis is:
T-LGL leukemia is a clonal CD8+/CD57+ disorder often linked to rheumatoid arthritis and neutropenia; STAT3 mutations are common. Proving clonality separates it from reactive LGL expansion.
In the Revised International Staging System for multiple myeloma, which two serum markers are combined with high-risk cytogenetics and LDH?
Staging uses serum beta-2 microglobulin (tumor burden and renal function) and albumin, adding LDH and high-risk FISH in the revised system. Calcium and creatinine are CRAB criteria for diagnosis, not staging.
A young adult has large 'hallmark' cells with horseshoe nuclei that are strongly CD30+ and ALK-positive. The typical genetic change is:
ALK-positive anaplastic large cell lymphoma usually carries t(2;5), fusing NPM1 with ALK; it has a relatively good prognosis in young patients. t(11;14) is mantle cell lymphoma.
AML blasts with cup-shaped nuclear invaginations, normal karyotype and aberrant cytoplasmic nucleophosmin are found. Without FLT3-ITD, this mutation is linked to:
NPM1-mutated AML is the most common AML with a normal karyotype and, without FLT3-ITD, has a favorable prognosis. It is a defining genetic abnormality in WHO 5th edition.
All-trans retinoic acid (ATRA) is effective in acute promyelocytic leukemia because it:
ATRA overcomes the transcription repression of PML::RARA, so promyelocytes mature into neutrophils; arsenic trioxide also degrades the fusion protein. CD33 binding describes antibody-drug conjugates.
Blasts are negative for myeloperoxidase and Sudan black B by cytochemistry but express CD13, CD33 and CD117 by flow cytometry, with no lymphoid markers. The best category is:
AML with minimal differentiation has fewer than 3% MPO-positive blasts on cytochemistry, so myeloid markers by flow are needed for diagnosis. Undifferentiated leukemia lacks lineage-specific markers.