Malignant glomus tumor: a case report and review of literature, focusing on its clinicopathologic features and immunohistochemical profile.

Malignant glomus tumor (MGT) is a rare, recently described neoplasm that recapitulates the appearance of the modified smooth cells of the normal glomus body. We report a case of MGT of the hand of a 48-year-old woman. Magnetic resonance imaging (MRI) showed a 2.8-cm, well circumscribed, enhancing mass on the volar aspect of the thenar region of the right hand in immediate continuity with the ulnar artery and nerve. Computed tomography scan (CT-Scan) of the chest was normal. Histologic evaluation revealed a multilobular lesion with prominent branching capillary vasculature and perivascular arrangement of sheets of tumor cells. The tumor cells were round, relatively uniform in size with distinct cell borders and perinuclear cytoplasmic clearing. They were of intermediate to high nuclear grade and showed significant mitotic activity. A wide local excision with negative margins was performed. Multiple lung metastases were evident at 8-month follow-up. To date, forty-five cases of MGT of skin and soft issue have been reported in the literature. Twelve of the forty-five cases developed metastasis. In this report, we emphasize the differential diagnosis of MGT in the skin and deep soft tissue.