[Lipoma arborescens].

Lipoma arborescens is a rare benign villous proliferation of fatty tissue in joints. It is most often affecting the knee, but it has also been reported in other joints. It may result from chronic irritation but can also be a primary condition. It is diagnosed primarily on MRI combined with the clinical presentation. The surgical treatment of choice is arthroscopic synovectomy. This case report presents a 44-year-old woman with longstanding knee pain due to lipoma arborescens. With increased awareness of this disorder, patients can benefit from proper and timely surgery.