Lipoma arborescens is commonly associated with osteoarthritis (OA) and joint trauma, although inflammatory arthritis has also been described1. This is the first known description of a positive anti-cyclic citrullinated peptide (anti-CCP) antibody in conjunction with lipoma arborescens2.
A 32-year-old woman presented with left knee pain. Symptoms that had begun 7 years previously had resolved with pregnancy and then recurred post-partum. Left knee corticosteroid injection was beneficial. She described recurrent swelling and difficulty kneeling and ascending stairs. She had a distant history of childhood idiopathic thrombocytopenic purpura and intermittent carpal tunnel symptoms. Physical examination showed a prominent Baker’s cyst, and left knee and bilateral wrist synovitis. Laboratory results including erythrocyte sedimentation rate, C-reactive protein, rheumatoid factor, and antinuclear antibodies were normal. Radiographs and bone scans were negative; aspiration was declined. Magnetic resonance imaging (MRI) scan of the knee showed evidence of lipoma arborescens. Bilateral wrist MRI showed bilateral diffuse tenosynovitis of flexor and extensor tendons, which responded to corticosteroid injections.
Knee synovectomy performed one year later resolved symptoms and confirmed the diagnosis. She was later found to be positive for anti-CCP antibody; she has early rheumatoid arthritis.
She declined disease modifying therapy. MRI of the knee showed a large suprapatellar effusion with frond-like fatty proliferation originating from the synovial membrane. This appearance is typical of lipoma arborescens, a rare benign intraarticular synovial lipoma that is metaplastic in nature (Figure 1). Typically, this condition affects a single knee joint3.
We describe a positive anti-CCP antibody in conjunction with lipoma arborescens2. This condition should be considered in patients who have recurrent symptoms and atypical presentations. MRI is diagnostic of this condition.