Hairy cell leukemia is a B-cell malignancy with characteristic hairy cytoplasmic projections. Which mutation is found in nearly all cases and is the target of vemurafenib?
- A t(11;14) producing cyclin D1 overexpression
- B BRAF V600E point mutation ✓
- C MYD88 L265P mutation
- D t(14;18) BCL2 rearrangement
Correct answer: B. BRAF V600E point mutation
Explanation
BRAF V600E mutation is found in virtually 100% of classic hairy cell leukemia cases, making it a defining molecular feature. This substitution locks BRAF in a constitutively active state, driving MEK/ERK signaling. Vemurafenib (BRAF inhibitor) is used in relapsed/refractory HCL. MYD88 L265P is characteristic of Waldenstrom macroglobulinemia. t(11;14) is mantle cell lymphoma. t(14;18) is follicular lymphoma.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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