An Unusual Exostosis of the Scapula Mimicking a Glenoid-Like Structure in Snapping Scapula Syndrome.

INTRODUCTION: Snapping scapula syndrome is an unusual condition characterized by an audible, grating, and snapping sound upon shoulder movement, often observed in young adults. Clinical severity ranges from gentle friction sounds to louder grating noises or crepitus, which may or may not be associated with pain and limited motion. Multiple etiologies include congenital malformations such as Sprengel's deformity, exostosis, subscapular mass, and scapulothoracic bursitis.

CASE PRESENTATION: A 28-year-old right-handed male presented a 12-year history of crepitus and snapping of the right scapula, with pain and worsening crepitus in the past year. Clinical examination revealed a symmetrical glenohumeral range of motion with combined scapular dyskinesia. CT scan showed a bony mass near the superior border and superomedial angle of the scapula, resembling a second glenoid with a smaller, less concave surface. The mass included a protuberance that suggested a second coracoid process and spine of the scapula. Surgical excision of the bony mass and surrounding bursa, along with partial resection of the superomedial angle, was performed. The patient fully recovered after 3 months and presented no symptoms of recurrence at the 2-year follow-up. The excised mass consisted of mature bony tissue with interspersed trabeculae, suggestive of exostosis.

CONCLUSION: Bone masses arising from the scapula vary in origin, presentation, and morphology. We describe a unique bony projection resembling a second glenoid, treated successfully with surgical resection and resulting in complete cosmetic and functional recovery.