Lipoma Arborescens of Subacromial-subdeltoid Bursa: Ultrasonographic Findings

The present study describes the ultrasound findings of lipoma arborescens arising in the subacromial-subdeltoid bursa. Ultrasound examinations were performed in seven shoulder joints of six patients with shoulder pain and functional limitations, as well as suspected rotator cuff abnormalities. Magnetic resonance imaging (MRI) was also performed in all cases. T1-weighted spin-echo and T2-weighted turbo spin-echo images, and a proton density-weighted sequence with fat spectral suppression or a short inversion time inversion recovery were obtained in a 1.5-T unit. Synovial-based hyperechoic villous proliferations and a diffuse synovial thickening associated with a sonolucent effusion in the subacromial-subdeltoid bursa were seen in all cases. Color Doppler showed no vascularisation in any of the cases. The fatty nature of the synovial hyperechoic proliferations was confirmed by MRI in all cases. In conclusion, ultrasonographic findings of lipoma arborescens arising in the subacromial-subdeltoid bursa suggest villous hyperechoic synovial proliferations associated with an effusion. Confirmation of the fatty nature of the synovial proliferation should be performed with MRI, which allows an unequivocal diagnosis.