A 58-year-old man presents with pancytopenia and moderate splenomegaly. Bone marrow aspiration yields a dry tap. Trephine biopsy shows interstitial infiltrates of medium-sized cells with abundant cytoplasm and a fried egg appearance, accompanied by marked reticulin fibrosis. Flow cytometry would most likely show positivity for which marker?

• A Tartrate-resistant acid phosphatase ✓
• B Terminal deoxynucleotidyl transferase
• C CD34
• D Cyclin D1

Explanation

Hairy cell leukaemia presents as a middle-aged man with pancytopenia, splenomegaly, a dry tap due to reticulin fibrosis, and fried egg cells. The neoplastic B cells characteristically express tartrate-resistant acid phosphatase along with CD11c, CD25, CD103, and annexin A1. Cyclin D1 positivity points to mantle cell lymphoma, and TdT marks lymphoblasts, so both fail to fit this picture.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.