SCYM Immunophenotyping 3 — Questions and Answers
Question 1: Which immunophenotypic pattern on flow cytometry is most consistent with follicular lymphoma?
- CD10+/BCL2+/CD19+/surface Ig+ (Correct answer)
- CD5+/CD23+/dim sIg+/CD200+
- CD103+/CD25+/CD11c+
- CD4+/CD8-/CD30+/ALK+
Correct answer: CD10+/BCL2+/CD19+/surface Ig+
Follicular lymphoma cells characteristically express CD10, BCL2, CD19, and surface immunoglobulin, reflecting their germinal center B-cell origin.
Question 2: In acute myeloid leukemia (AML), which marker combination suggests monocytic differentiation (AML-M5)?
- CD13+/CD33+/CD64+/CD14+ (Correct answer)
- CD34+/CD117+/HLA-DR+/MPO+
- CD41+/CD61+/CD42b+
- CD19+/CD22+/TdT+
Correct answer: CD13+/CD33+/CD64+/CD14+
Monocytic AML (FAB M5) is characterized by expression of myeloid markers plus monocyte-associated antigens CD14 and CD64.
Question 3: Which surface marker helps distinguish mantle cell lymphoma from CLL when both diseases co-express CD5 and CD19?
- CD23 negativity in MCL (Correct answer)
- CD20 positivity in CLL
- CD38 in CLL
- HLA-DR in MCL
Correct answer: CD23 negativity in MCL
Mantle cell lymphoma is typically CD23-negative, while CLL is CD23-positive, making this a key discriminating marker between these two CD5+ B-cell neoplasms.
Question 4: In immunophenotyping of T-cell acute lymphoblastic leukemia (T-ALL), which marker indicates early T-cell precursor (ETP-ALL) subtype?
- CD1a expression
- CD34 and CD117 co-expression with absent CD5 (Correct answer)
- Bright CD3 with CD4/CD8 double positivity
- CD10 and TdT co-expression
Correct answer: CD34 and CD117 co-expression with absent CD5
ETP-ALL is defined by expression of stem cell/myeloid markers (CD34, CD117) with absent or dim CD5 and no CD1a, reflecting arrested early T-cell development.
Question 5: Which antigen is characteristically expressed on Reed-Sternberg cells of classical Hodgkin lymphoma as detected by flow cytometry or immunohistochemistry?
- CD30 and CD15 (Correct answer)
- CD20 and CD79a
- CD3 and CD5
- CD138 and CD38
Correct answer: CD30 and CD15
Reed-Sternberg cells in classical Hodgkin lymphoma characteristically express CD30 (Ki-1 antigen) and CD15, while lacking most B-cell and T-cell markers.
Question 6: When immunophenotyping a bone marrow sample for multiple myeloma, which marker combination most specifically identifies the malignant plasma cells?
- CD138+/CD38+/CD19-/CD56+ (Correct answer)
- CD19+/CD20+/CD5+/CD23+
- CD34+/CD117+/HLA-DR+
- CD3+/CD4+/CD8-/CD45RO+
Correct answer: CD138+/CD38+/CD19-/CD56+
Myeloma plasma cells are CD138+/CD38+ (bright) and characteristically lack CD19 while often aberrantly expressing CD56.
Question 7: Dim CD45 expression combined with low side scatter is most characteristic of which bone marrow cell population?
- Mature granulocytes
- Lymphocytes
- Blasts (hematopoietic precursors) (Correct answer)
- Plasma cells
Correct answer: Blasts (hematopoietic precursors)
Hematopoietic blasts typically fall in the CD45-dim/low SSC region of the CD45 vs SSC blast gate, distinguishing them from mature lymphocytes (CD45-bright/low SSC) and granulocytes (CD45-dim/high SSC).
SCYM Immunophenotyping 3
Which immunophenotypic pattern on flow cytometry is most consistent with follicular lymphoma?