The purpose of this study was to define MR imaging of patients with lipoma arborescens of the knee.
MR images showed villous lipomatous proliferation (100%) with signal intensity similar to that of fat on T1- and T2-weighted images, masslike subsynovial fat deposition (38%), joint effusion (100%), erosive bone changes at articular margins (38%), associated synovial cysts (25%), and degenerative changes (13%). MR imaging is a valuable technique for examining patients with lipoma arborescens of the knee and can support the diagnosis of this rare condition.