BRAF and KRAS mutations in sporadic glomus tumors.

Glomus tumors are rare soft tissue neoplasms resembling the normal glomus body, which is a specialized form of arteriovenous anastomosis that regulates heat. The molecular genetics of sporadic glomus tumors has not been studied. We genotyped tumors from 28 patients (16 female patients and 12 male patients) ranging from 13 to 77 years and correlated the results with the tumor site (15 finger/1 hand/4 arm/7 leg/1 eyelid), Ki-67 index, and clinical follow-up. Tumor DNA from paraffin-embedded tissue was screened by multiplex polymerase chain reaction and mass spectroscopy, using a panel covering 370 mutations across 30 genes, including AKT1, BRAF, CTNNB1, EGFR, ERBB2, FGFR1/2/3, HRAS, KIT, KRAS, MEK1/2, NRAS, PDGFRA, and PIK3CA. A BRAF V600E mutation was identified in 3 cases, all of which occurred in proximal locations (upper shin, thigh, and upper arm). Two of the patients with BRAF-mutated tumors were quite young (21 and 13 years) and one of the BRAF-mutated tumors recurred in 3 years. A KRAS G12A mutation was found in tumor removed from the finger. Ki-67 index did not correlate with genotype. To our knowledge, this is the first report of oncogenic mutations in sporadic glomus tumors.