A 58-year-old man has fatigue and massive splenomegaly. CBC shows pancytopenia with an absolute monocytopenia. Bone marrow aspiration yields a dry tap; trephine biopsy shows interstitial infiltration by mononuclear cells with abundant cytoplasm and fried-egg appearance. Tartrate-resistant acid phosphatase staining is positive. Which flow cytometry profile is characteristic?
- A CD19+, CD11c+, CD25+, CD103+ ✓
- B CD19+, CD5+, CD23+, dim surface Ig
- C CD19+, CD10+, surface Ig strong, TdT+
- D CD38+, CD138+, cytoplasmic kappa restriction
Correct answer: A. CD19+, CD11c+, CD25+, CD103+
Explanation
Hairy cell leukaemia classically shows the CD11c, CD25 and CD103 triple positivity, annexin B1 expression, TRAP positivity, splenomegaly, monocytopenia and a dry tap. Option B is the immunophenotype of chronic lymphocytic leukaemia, where CD5 and CD23 positivity and absence of monocytopenia distinguish it; hairy cells are CD5 and CD23 negative. Treatment is a purine analogue such as cladribine.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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