A 58-year-old man has massive splenomegaly and pancytopenia with a dry bone marrow tap. Marrow smear shows mononuclear cells with abundant cytoplasm and hair-like villous projections arranged in a fried egg pattern. Which cytochemical stain is classically positive?
- A Periodic acid-Schiff
- B Myeloperoxidase
- C Tartrate-resistant acid phosphatase ✓
- D Non-specific esterase
Correct answer: C. Tartrate-resistant acid phosphatase
Explanation
Hairy cell leukaemia is a mature B-cell neoplasm of middle-aged men presenting with pancytopenia, monocytopenia, massive splenomegaly and dry tap. The cells are classically tartrate-resistant acid phosphatase (TRAP) positive and express CD11c, CD25, CD103 and annexin C1. Myeloperoxidase marks myeloid blasts, non-specific esterase marks monocytic lineage, and neither is positive in hairy cells.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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