Aspiration cytology of glomus tumor: a case report

Glomus tumor is a relatively uncommon soft tissue tumor that can occur at any age and anatomic site, with a predilection for the subungual region.

A 24-year-old female presented with a gradually enlarging, painful swelling in the subungual region of the right index finger. Fine needle aspiration was performed under a ring block and yielded hemorrhagic material. The smears revealed clusters of uniform, round to oval cells admixed with wisps of magenta intercellular myxoid material and a few spindle-shaped cells crossing clusters of tumor cells. A diagnosis of benign vascular tumor consistent with glomus tumor was given. Subsequent histopathologic examination confirmed the diagnosis and showed alpha-SMA positivity on immunohistochemistry.

This case report is the second on the cytologic features of glomus tumor in the English-language literature. Although the cytomorphologic features of glomus tumor are quite distinctive, an appropriate clinical history and immunohistochemical stains (e.g., alpha-SMA and vimentin positivity) can further help to ascertain the diagnosis.