Sonographic features of diffuse giant cell tumor of the tendon sheath in the shoulder: A case report.

A middle-aged woman presented to our hospital with a chief complaint of a mass on the left shoulder for 1 year. The initial lump was small with no pain or tenderness, and the patient had not sought medical attention for numbness in the left shoulder. Clinical examination showed a mass on the left shoulder measuring 11 × 8 × 3 cm approximately with no apparent skin damage or ecchymosis. No limitations in left shoulder joint movements were observed, and the patient exhibited normal movement of the left elbow joint, wrist joint, and metacarpophalangeal joint. Moreover, the left radial artery was palpable.