Combined arthroscopic and open operative management of an intramuscular supraspinatus lipoma in the treatment of subacromial impingement syndrome: A case report

INTRODUCTION: Subacromial impingement syndrome (SAIS) is one cause of shoulder pain and encompasses a spectrum of pathologies and is not an isolated entity. PRESENTATION OF CASE: We present a rare case where a 40 year old male presented with a 3 year history of right shoulder tip pain with limited abduction to 30°, external rotation to 45°, preserved internal rotation and forward flexion and a painful arc with positive Neers and Hawkins-Kennedy signs for impingement consistent with SAIS. The presentation occurred in the setting of a supraspinatus intramuscular lipoma demonstrated on shoulder MRI. This was managed operatively with a combined arthroscopic and open approach to allow performance of a bursectomy, debridement of mild acromioclavicular joint degeneration and lipoma excision. The patient was discharged on the first post-operative day. He was managed in a sling for 4 weeks with a graduated exercise program over the first 12 weeks with full shoulder strength and function maintained at 12 months. DISCUSSION: Lipoma as a cause of SAIS is rare but an important diagnosis that needs to be considered in the preoperative evaluation of SAIS to guide appropriately targeted surgical management. CONCLUSION: This case reinforces the diversity of pathologies in SAIS and the breadth of differential diagnoses that need to be considered when evaluating and determining the appropriate surgical approach to maximise chance of symptom resolution in SAIS.