Haemothorax Caused by Isolated Costal Exostosis

We report an unusual case of spontaneous haemothorax in a 13-year-old girl with isolated costal exostosis. Surgical excision of the exostosis was performed with complete resolution. Costal exostosis should be considered in the differential diagnosis of spontaneous haemothorax in children in order to avoid unnecessary investigation and to establish an adequate treatment plan.