Lipoma Arborescens: Imaging Features of Typical and Atypical Disease and Differentiation From Other Intra-articular Pathology

Lipoma arborescens is a benign intra-articular lesion characterized by villous lipomatous proliferation of the synovium. It is most commonly found in the knee joint. However, lipoma arborescens also may be found in other joints and bursae and tendon sheaths. The purpose of this educational activity is to review typical and atypical cases of lipoma arborescens. In this article, we review the clinical features of lipoma arborescens. Its imaging characteristics on different radiologic modalities are reviewed. Histologic findings are examined to explain its imaging appearance. Differential diagnosis is discussed, including means to distinguish them by imaging. Correct diagnosis prevents misdiagnosis that may lead to unnecessary additional clinical evaluation and prompts referral to an orthopedic surgeon for evaluation for definitive treatment.