Patient with psoriasis and a history of swelling interphalangeal joints and knees.

On X-ray images there are erosive bone changes and a hyperdense knee effusion.

On MRI, evaluation of the soft tissue reveals a large amount of intraarticular fluid, hypertrophied enhancing synovia, and frond-like synovia containing fat.  Evaluation of the bone shows bone erosions and osteophytes.

The findings overall suggest diagnosis of chronic synovitis with lipoma arborescens.