A 48-year-old man presents with an exquisitely painful, raised, red lesion on the dorsal surface of his left hand. Histologic examination of a skin biopsy reveals nests of round regular cells within connective tissue associated with branching vascular spaces. Which of the following is the most likely diagnosis?

A glomus tumor is a benign tumor of the glomus body, which is often extremely painful. Glomus bodies are normal neuromyoaerial receptors that are sensitive to temperature and regulate aeriolar blood flow. The lesions are small, usually smaller than 1 cm in diameter. The two main histologic components are branching vascular channels in connective tissue stroma and aggregates of specialized glomus cells. The other choices tend not to be painful.