Hemothorax caused by costal exostosis injuring diaphragm: a case report and literature review

BACKGROUND: Osteochondromas, also known as exostoses, are the most common benign tumors of bone and can be classified into isolated and multiple osteochondromas. A great majority of osteochondromas is asymptomatic, painless, slow-growing mass, and incidentally found. However, osteochondromas occurring in adolescence or in adult patients can grow in size and become symptomatic as a result of mechanical irritation of the surrounding soft tissues or peripheral nerves, spinal cord compression, or vascular injury. CASE PRESENTATION: We present a case of a 13-year-old girl with spontaneous hemothorax, the cause of which was identified by limited thoracotomy with the aid of video-assisted thoracic surgery to be bleeding from a diaphragmatic laceration incurred by a costal exostosis on the left sixth rib. Preoperative chest computed tomography (CT) depicted a bony projection arising from the rib and bloody effusion in the intrathoracic cavity, but was unable to discern the bleeding cause from the lung or the diaphragm. This case will highlight our awareness that costal exostosis possibly results in bloody pleural effusion. Meanwhile, English literatures about solitary costal exostosis associated with hemothorax were searched in PubMed and nineteen case reports were obtained. Combined our present case with available literature, a comprehensive understanding of this rare disease entity will further be strengthened. CONCLUSIONS: Injury to the diaphragm is the primary cause of hemothorax caused by costal osteochondroma, including the present case. Thoracic CT scan can help establish a diagnosis of preoperative diagnosis of costal osteochondroma. Surgical intervention should be considered for those patients with symptomatic osteochondroma of the rib. Combined with our case and literature, prophylactic surgical removal of intrathoracic exostosis should be advocated even in asymptomatic patients with the presentation of an inward bony spiculation.