An unusual cause for anterior knee pain: strangulated intra-articular lipoma.

Lipoma is the most frequently encountered benign soft tissue tumor. However, intra-articular lipomas are rarely seen. Anterior knee pain is a frequent complaint of adults and is of diverse etiology. This 42-year-old female patient had severe anterior knee pain, unresponsive to medical treatment. Magnetic resonance imaging revealed an intra-articular tumor of the knee joint. Arthroscopic intervention and subsequent histological examination resulted in the diagnosis of strangulated lipoma originating from infrapatellar fat pad. We present clinical, radiological and operative features of this rare case of intra-articular lipoma.