SCYM Immunophenotyping 5

Question 1

In immunophenotyping of chronic myelomonocytic leukemia (CMML), which monocyte subset ratio abnormality is diagnostically significant?

Accepted Answer

Classical monocytes (CD14+/CD16-) >94% of total monocytes

Answer

CMML is characterized by a predominance of classical monocytes (CD14+/CD16-) comprising >94% of all monocytes, distinguishing it from reactive monocytosis where non-classical monocytes increase.

Question 2

Which surface marker combination identifies regulatory T cells (Tregs) by flow cytometry?

Accepted Answer

CD4+/CD25high/CD127low

Answer

Regulatory T cells are identified as CD4+/CD25high/CD127low, with FOXP3 intracellular staining providing additional confirmation.

Question 3

When evaluating a CD34+ blast population in AML for megakaryoblastic lineage (AML-M7), which markers should be included in the panel?

Accepted Answer

CD41, CD61, and CD42b

Answer

Megakaryoblastic differentiation is confirmed by expression of platelet glycoproteins CD41 (GPIIb), CD61 (GPIIIa), and CD42b (GPIbα).

Question 4

Which flow cytometric finding in a cerebrospinal fluid (CSF) specimen would best support leptomeningeal involvement by CLL?

Accepted Answer

CD5+/CD19+/CD23+/dim sIg+ B cells with clonal light chain restriction

Answer

Detection of clonal CD5+/CD19+/CD23+ B cells with dim surface immunoglobulin and light chain restriction in CSF confirms leptomeningeal CLL involvement.

Question 5

In post-transplant lymphoproliferative disorder (PTLD) immunophenotyping, which EBV-associated antigen can be detected by flow cytometry to support the diagnosis?

Accepted Answer

EBV-LMP1 detected by intracellular flow staining

Answer

EBV latent membrane protein 1 (LMP1) can be detected by intracellular flow cytometry on infected B cells, supporting EBV-driven PTLD in immunosuppressed patients.

(SCYM) Specialist in Cytometry Practice Test

(SCYM) Specialist in Cytometry Practice Test

SCYM Immunophenotyping 5