Growing wrist mass

A 46 year old man presented with a growing mass over his wrist. Erosions of the triquetrum and hamate were present radiographically. Magnetic resonanc e imaging (MRI) showed a solid mass arising from the extensor carpi ulnaris tendon, which was T-1 hypointense and isointense, T-2 hypointense, and blo omed on gradient echo images. The preoperative diagnosis of giant cell tumo ur of the tendon sheath was confirmed on histopathological examination of t he excised specimen. The clinical, pathological, and imaging features, with emphasis on MRI findings, of this condition are reviewed.