Lipoma Arborescens of the Knee

Lipoma arborescens is a rare intraarticular lesion consisting of lipomatous proliferation of the synovium. It tends to occur in the knee joint, especially within the suprapatelar pouch.

MR findings include a large fatty mass with fronds (hence arborescens: Latin for tree-like) that arises from the synovium with an associated effusion.

References

Feller JF, Rishi M, Hughes EC. Lipoma arborescens of the knee: MR demonstration. AJR Am J Roentgenol. 1994 Jul;163(1):162-4.