Hairy cell leukemia is characterized by a somatic point mutation in which gene, found in virtually 100% of cases?

• A BRAF V600E ✓
• B JAK2 V617F
• C CALR exon 9
• D NPM1

Explanation

BRAF V600E mutation is present in essentially all classic hairy cell leukemia cases, making it both a diagnostic marker and a therapeutic target (vemurafenib). The neoplastic B cells express CD11c, CD25, CD103, and annexin A1 on flow cytometry. JAK2 V617F is the hallmark of polycythemia vera. CALR mutations occur in ET and PMF. NPM1 mutations are common in AML with normal karyotype. Testing for BRAF V600E distinguishes classic HCL from its variant and from splenic marginal zone lymphoma.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.