Lipoma arborescens

T1 and PDFS sagittal images of the left knee of a 27 year old male with history of recurrent joint swelling for the last two years showing frond like synovial thickening in the suprapatellar and posterior parts of the knee joint. The intensity of the frond like synovial thickening is suggestive of fatty tissue.There is significant synovial effusion.

-Lipoma arborescens is a rare condition affecting synovial lining of joints and bursae.
-Usually unilateral
-Most common joint affected-knee
-Rare in other joints like hip, shoulder, wrist. elbow
-There is frond like deposition of fat in the synovial lining.
-Clinical presentation is usually of painless recurrent joint effusion
-MRI is diagnostic as it shows the fatty nature of the fat deposition most commonly in the suprapatellar region of the knee joint.
-Treatment is synovectomy. It usually does not recur after surgery.
- Differentials are: synovial chondromatosis, PVNS, synovial hemangioma, inflammatory arthritis.