Case report 749: Primary glomus tumor of bone

We report a case of primary intraosseous glomus tumor in a 30-year-old man who was found to have an expanding, lytic lesion in the distal phalanx of his left thumb. The histological appearance was atypical in that areas of myxoid stroma resembled chondroid material. The unusual location and microscopic appearance caused diagnostic problems. Immunohistochemical studies, including strong positive staining for MSA and negative staining for keratin and S-100 protein, were helpful in establishing the correct diagnosis.