Abstract

A 30-year-old woman presented with swelling in her right thumb of 3-month duration which was slow-growing in nature without a history of trauma. On examination, firm non-tender swelling with ill-defined border over the dorsomedial aspect of the first metacarpal was noted. The swelling was mobile only in the vertical plane with restricted adduction and abduction. Plain X-ray revealed mild erosion of the first metacarpal head. Diagnostic ultrasound confirmed the lesion to arise from the extensor tendon sheath of diffuse type without any bony involvement. A wide local excision biopsy of the swelling was planned. Intraoperatively, a 3×2 cm greyish-white mass, bony hard in consistency with lobulated surface was found arising from the tendon sheath of the extensor tendon of the thumb; it was completely excised with a wide margin. Histopathological examination revealed polyhedral cells admixed with osteoclastic type giant cells. Biopsy from the first metatarsal was normal. The patient is on follow-up for the last 5 years with no evidence of recurrence.