Abstract
BACKGROUND: Hereditary multiple exostosis (HME) is characterised by multiple osteochondromas that are distributed throughout the skeleton, invariably involving the shoulder girdle. Tumours within the subacromial space can cause secondary irritation of the rotator cuff and result in subacromial impingement syndrome. CASE PRESENTATION: We describe a 19 year old female patient with HME who presented with subacromial impingement syndrome secondary to a benign exostosis originating from the spine of the scapular and projecting into the subacromial space. CONCLUSION: The unique aspects of this report was that the origin of the exostosis, which was not observed on early standard radiographs of the shoulder, and the use of arthroscopic excision of the exostosis. Hence we believe a low threshold for additional imaging, such as a magnetic resonance imaging, should be considered for patients with HME with subacromial impingement syndrome to ensure a symptomatic exostosis is not neglected. Arthroscopic excision of a benign subacromial exostosis is effective, offering a minimally invasive approach with relief of the patient's symptoms.