Recently, a BRAF V600E mutation-specific monoclonal antibody has been developed [26] and validated as a reliable test among tumors that frequently harbor the BRAF V600E mutation, including primary and metastatic melanoma [18,20,27,28], papillary thyroid carcinoma [29,30], hairy cell leukemia [31], ovarian serous borderline tumors [32], primary lung adenocarcinomas [33], as well as in a large series of brain metastases and corresponding non-CNS primary tumors [34]. Here, BRAF is linked to hairy cell leukemia.