A rapidly growing cutaneous malignant glomus tumor with a CCND3 mutation.

Glomus tumors are rare mesenchymal neoplasms composed of cells resembling the glomus body. They are most frequently seen in subungual regions but have been reported to arise in almost every anatomic location. Malignant glomus tumors, also called glomangiosarcomas, of cutaneous origin are exceedingly rare with only 47 reported cases. The genetic alterations that lead to the development of cutaneous malignant glomus tumors are not well understood. Small studies report glomus tumors with mutations in glomulin (GLMN), NF1, BRAF, NOTCH, PDGFRB, KRAS, and SMARCB1. These mutations have mostly been studied in deep or visceral glomus tumors. We report a case of a cutaneous malignant glomus tumor with a CCND3 point mutation identified on next generation sequencing, without any of the previously described genetic mutations. CCND3 mutations that cause cyclin D3 amplification may prove to be targets for CDK4/6 inhibitors in the treatment of malignant glomus tumors.