True Intra-Articular Lipoma of the Knee: A Case Report

Although lipomas are the most common benign soft tissue tumor, very few cases of true intra-articular lipomas have been described. They are usually small in size and located at the knee. The differential diagnosis of an intra-articular lipomatous mass is made between lipoma arborescens and synovial lipoma. We report a case of a true intra-articular lipoma of the knee in a 60-year-old woman who presented with knee pain and a large anteromedial mass. The magnetic resonance imaging (MRI) confirmed the presence of a well-delineated fat-containing mass, and the lipoma was excised by a standard medial arthrotomy. After two years, the patient reported no limitation in her daily life.