SCYM Clinical Applications 3

Question 1

A pleural effusion specimen shows a predominant population of T cells with CD4+/CD8- phenotype and aberrant loss of CD7. What does CD7 loss suggest?

Accepted Answer

T-cell lymphoma involvement

Answer

Aberrant loss of pan-T-cell antigens such as CD7 in a T-cell population is a hallmark of T-cell lymphoma rather than a reactive process.

Question 2

In the diagnosis of systemic mastocytosis, which immunophenotypic aberrancy is most diagnostic on mast cells?

Accepted Answer

Aberrant CD25 and/or CD2 expression

Answer

Neoplastic mast cells in systemic mastocytosis aberrantly express CD25 and/or CD2, which are absent on normal mast cells.

Question 3

Which marker combination best identifies natural killer (NK) cells in peripheral blood by flow cytometry?

Accepted Answer

CD56+/CD16+/CD3-

Answer

Mature NK cells are defined by CD56 and CD16 positivity with absence of CD3, distinguishing them from NKT cells.

Question 4

In acute myeloid leukemia (AML), which immunophenotype is associated with acute promyelocytic leukemia (APL/AML-M3)?

Accepted Answer

CD33+/CD13+/HLA-DR-/CD34-

Answer

APL blasts are typically CD33+/CD13+ but characteristically lack HLA-DR and CD34, which is diagnostically important.

Question 5

For minimal residual disease (MRD) detection in B-ALL, which immunophenotypic combination is most used as a leukemia-associated immunophenotype (LAIP)?

Accepted Answer

Aberrant CD66c or CD45 dim with TdT+/CD10+/CD19+

Answer

LAIPs in B-ALL commonly include aberrant expression of myeloid antigens like CD66c or abnormal CD45 levels within the immature B-cell gate.

(SCYM) Specialist in Cytometry Practice Test

(SCYM) Specialist in Cytometry Practice Test

SCYM Clinical Applications 3