Incidental Intraoperative Finding of Bilateral Lipoma Arborescens in a Patient Undergoing Bilateral Total Knee Replacement.

Lipoma arborescens (villous lipomatous proliferation of the synovial membrane) is a rare, benign articular lesion characterized by diffuse villous proliferation of the synovium with mature fat substitution of the sub-synovial connective tissue. The etiology of this condition still remains unknown. It represents part of differential diagnosis for a progressive swollen knee with chronic pain secondary to synovial proliferative disorders with or without associations with osteoarthritis. We report an intraoperative finding of lipoma arborescence in a patient who underwent bilateral primary total knee replacement secondary to advanced osteoarthritis.