Case report 873: Lipoma arborescens (villous lipomatous proliferation of the synovial membrane).

A case of lipoma arborescens with typical features was presented. MR imaging established the preoperative diagnosis by visualizing the typical frond-like synovial projections containing fatty tissue. The extent of joint involvement must be fully documented because an open synovectomy is most appropriate in the management of this disease. Although lipoma arborescens is a rare condition, it is important to recognize the MR features due to the large volume of MR examinations of the knee which are performed.