Sporadic Malignant Glomus Tumor of the Brachial Plexus With Response to Targeted Therapy Directed Against Oncogenic BRAF

Glomus tumors are rare mesenchymal neoplasms usually involving the dermis, typically found in a subungual location, and historically hypothesized to arise from cells of the glomus body, an arteriovenous shunt involved in temperature regulation.1,2 The majority of these tumors are benign, although some exhibit more aggressive biologic features and clinical behavior (malignant glomus tumor, or glomangiosarcoma). Others have an intermediate phenotype and are classified as glomus tumors of uncertain malignant potential (GT-UMP).3 Herein, we present a case of an 18-year-old patient with two glomus tumors involving the lateral and posterior cords of the right brachial plexus. The magnetic resonance (MR) imaging, intraoperative and histologic findings, therapeutic approach, and unique response to molecularly targeted therapy are discussed.