A 58-year-old man presents with fatigue and abdominal discomfort. Examination shows massive splenomegaly without lymphadenopathy. CBC shows pancytopenia. Bone marrow aspirate yields a dry tap, and trephine biopsy shows interstitial infiltration by mononuclear cells with abundant pale cytoplasm and circumferential cytoplasmic projections. The cells show strong tartrate-resistant acid phosphatase positivity and express CD11c, CD25, and CD103. First-line treatment?

• A Rituximab-bendamustine chemoimmunotherapy
• B Imatinib 400 mg daily
• C Hydroxyurea with periodic phlebotomy
• D Cladribine as a single course ✓

Explanation

The constellation of splenomegaly, pancytopenia, dry tap from marrow fibrosis, hairy cells expressing CD11c, CD25, CD103, and annexin A1 positivity establishes hairy cell leukaemia. Purine analogue therapy with cladribine (or pentostatin) produces durable complete remissions in most patients after a single course and is standard first-line treatment. Rituximab-based regimens serve relapsed disease, imatinib targets BCR-ABL in CML, and hydroxyurea does not affect the neoplastic clone.

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.