Lipoma arborescens: a rare cause of clicking in the knee.

Lipoma arborescens (LA) is a rare condition with synovial membrane lipomatous proliferation. It most commonly affects the knee joint, in the suprapatellar pouch. It can present as a painful knee with an effusion. Diagnosis is via MRI demonstrating a synovial mass with frond-like appearance, and histology showing mature adipose cells, with an overlying synovial membrane. Treatment options include non-operative measures with analgesia, or operative intervention to resect the lesion. We describe a unique case of LA present in the anterolateral knee joint, presenting with persistent painful clicking in the knee. The patient underwent an open total resection of the lesion, with resolution of symptoms.