A rare presentation of a large suprascapular fossa lipoma causing suprascapular nerve traction injury leading to massive rotator cuff tear, treated arthroscopically – case report

Suprascapular fossa lipoma extending to the suprascapular notch causing traction injury to the suprascapular nerve is a rare presentation. We report a 47 year old male with progressive weakness of the right shoulder joint of 8 months duration, with a palpable mass over the the spine of scapula noticed 2 months earlier, and developed a sudden drop arm following a moderate strain. Magnetic resonance imaging (MRI) scan revealed a rotator cuff tear involving the supraspinatus and infraspinatus muscles with a tumour like lesion in the suprascapular fossa displacing the suprascapular muscle mass and extending into the suprascapular notch. Electromyography and nerve conduction velocity studies revealed suprascapular neuropathy. After histopathologic confirmation, an arthroscopic excision of the mass with decompression of the suprascapular notch were preformed along with repair of the rotator cuff. 6 month after the procedure the patient had improved considerably in terms of function and post-operative MRI revealed a complete excision of the mass, and further follow-up of 2 years showed no recurrence.Suprascapular nerve entrapment can be caused by a Lipoma in the shoulder leading to weakness, atrophy and consequent tear of the rotator cuff tendons. Arthroscopic management, after histopathological confirmation, gives good results in this situation.Level of EvidenceLevel IV