Snapping shoulder?

66yr lady with rotator cuff tendinosis and a clicking scapula.

Elastofibroma dorsi is a pseudotumour consisting of fibroelastic tissue which presents as a painless mass producing clicking on forward scapular motion.The typical appearance is a mass which is isointense to muscle with fatty components deep to the scapula(in this case deep to serratus). Repetitive trauma has been suggested as aetiology. I guess most clinicians would prefer to prove it with a biopsy rather than risk a liposarcoma.