Congenital first and second rib fusion causing neurogenic thoracic outlet syndrome in an adolescent

A 14-year-old girl presented with progressive right-sided neck and shoulder pain and ulnar-distribution paresthesia, consistent with neurogenic thoracic outlet syndrome. Computed tomography imaging revealed congenital fusion of the right first and second ribs causing brachial plexus compression. Conservative therapy was ineffective, and she underwent a transaxillary resection of the fused right first and second ribs with anterior scalenectomy. Intraoperatively, dense periosteal scarring and brachial plexus entrapment were identified. Symptoms fully resolved postoperatively. Congenital first-second rib synostosis is an exceptionally rare cause of pediatric neurogenic thoracic outlet syndrome. Early recognition and surgical decompression can prevent chronic disability and restore normal function.