BRAFV600E mutation in hairy cell leukemia: A single-center experience

BRAFV600E mutation has been reported as a unique genetic lesion of hairy cell leukemia (HCL), a subset of which lacks this lesion and shows adverse outcomes.

To determine the prevalence of BRAFV600E in HCL from our center and derive clinicopathological correlation, if any.

A 9-year retrospective analysis of 46 consecutive cases of HCL diagnosed on morphology and immunophenotyping was done. Stained smears were used as samples for amplification refractory mutation system polymerase-chain reaction using fluorescent primers for mutation detection.

BRAFV600E mutation was detected in 41/46 patients (89.1%) while absent in control samples of chronic lymphocytic leukemia. Cases mimicking HCL-variant clinically or immunophenotypically too showed the presence of this mutation. HCL with mutated BRAF presented at a younger age. No statistical difference in blood counts, tumor load, and immunophenotype patterns existed among BRAF mutated and unmutated group. Nine patients (45%) with mutated BRAF had residual disease following treatment with cladribine.

BRAFV600E mutation analysis has a definitive role in the diagnosis of HCL.