[Compression of the subscapular nerve in the spino-glenoid tract by a synovial cyst].

We observed a case of synovial cyst in the shoulder joint leading to spino-glenoid symptomatology in a weight-lifter. Explorations included standard radiography, echography and magnetic resonance imaging. Differentiation between a true cyst and a pseudo-cyst was basedose presence of a synovial membrane. Mechanical contraints appear to be the most frequently suspected aetiology of spinoglenoid cysts. Echography cannot always confirm the liquid nature of the formation due to the close bone. Magnetic resonance imaging gives good tissue characterization and good topographic analysis. Gadolinium injection appears to be important for differential diagnosis with neurogenic tumours.