Lipoma arborescens of the knee

Lipoma arborescens is a rare intraarticular lesion characterized by diffuse replacement of the subsynovial tissue by mature fat cells, producing villo us transformation of the synovium. The etiology of this benign condition is unknown. The most typical site of involvement is the knee, most notably at the suprapatellar pouch, although other joints can be affected. Symptoms c onsist of gradual joint swelling, variable pain, motion range restriction, and intermittent joint effusions or bleeding. We report a case of lipoma ar borescens and discuss the clinical features, diagnosis, and treatment of th is disorder based on a literature review. Although it is rare, lipoma arbor escens should be included in the differential diagnosis of patients with ch ronic joint swelling or hemarthrosis.