Solitary intra-articular soft tissue mass with a differential diagnosis of tenosynovial giant cell tumor, desmoid tumor and atypical ganglion cyst.

The musculoskeletal radiologist and oncologic orthopedic surgeon reviewed the case. The patient underwent an ultrasound-guided biopsy of the lesion, followed by its complete surgical excision.

Histopathological analysis of both specimens confirmed a tenosynovial giant cell tumor with a prominent xanthomatous component. No evidence of malignancy seen.