[1452] BRAF V600E Mutation Is Consistently Absent in Hairy Cell Leukemia Variant: A Retrospective Analysis Using Pyrosequencing

Parisa Khalili, Devon Chabot-Richards, James Gale, Mohammad A Vasef. University of New Mexico, Albuquerque, NM; TriCore Reference Laboratories, Albuquerque, NM

Background: The distinction between classic hairy cell leukemia (HCL) and so-called hairy cell leukemia variant (HCL-v) can be problematic because HCL-v cases share many immunophenotypic and immunohistochemical features with classic HCL. Recent studies have demonstrated that virtually all classic HCL harbor BRAF V600E mutation. However, to the best of our knowledge, the status of BRAF V600E mutation has not been studied in so-called HCLv cases.
Design: From the archival files of the Department of Pathology at the University of New Mexico, we identified 10 cases including 5 classic HCL and 5 HCL-v that had been previously characterized based on combined morphologic and immunophenotypic features using 2008 WHO criteria for classification of lymphoid neoplasms. Representative paraffin embedded bone marrow clot or splenic sections were selected following morphologic review to ensure adequate tumor representation for BRAF V600E mutation analysis. Briefly, the DNA was extracted and subjected to PCR amplification of 135 bp products containing codon 600 of BRAF gene followed by pyrosequencing of codons 599-601.
Results: Analysis of pyrograms showed BRAF V600E mutation in all cases with previously characterized diagnosis of classic HCL. In contrast, none of the HCL-v cases showed the BRAF V600E mutation.
Conclusions: Based on our results, analysis of BRAF V600E mutation can prove helpful in separating classic HCL from HCL-v in problematic cases since this mutation is consistently absent in HCL-v cases. This is in contrast to classic HCL in which the BRAF V600E mutation is detectable in virtually all cases as demonstrated by our study as well as prior published data. Future studies with larger number of cases may be necessary to further confirm our observations.
Category: Hematopathology

Monday, March 19, 2012 1:00 PM

Poster Session II # 225, Monday Afternoon


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