Lipoma arborescens and synovial chondromatosis with subacromial bursal effusion

Lipoma arborescens (LA) is a disease in which mature adipose tissue grows within joints and bursae, predominantly in the knee joint, but rarely in other joints. In this paper, we report a case of synovial chondromatosis of the subacromial bursa diagnosed as LA. A 74-year-old female patient had a mass in her right shoulder; MRI showed diffuse villous proliferation of the synovium within the subacromial bursa, and revealed a chemical shift artifact. We suspected LA and two nodules in the long head of the biceps tendon appeared to be chondromatosis. The surgery was performed and the subacromial bursa and nodules was removed. After histopathologic examination, a diagnosis of LA and synovial chondromatosis was made. Five years after surgery, there was no tumor recurrence. LA can be diagnosed by MRI. Recognition of clinical and imaging findings is essential for early diagnosis and treatment.