A costal exostosis may cause a spontaneous hemothorax or hemopneumothorax.
Mechanism: uncertain. It may be related to frictional irritation and inflammation, especially over an area with an irregular angulation.
The hemothorax may occur at any age but often in an adolescent or young adult.
The patient may have one or more exostosis.
Risk factors:
(1) hereditary multiple exostoses
(2) coagulopathy
(3) irregular or angulated exostosis (versus smooth and regular)
An exostosis may not be seen on a plain chest X-ray. CT or MRI may be more sensitive in identifying a small exostosis.
The diagnosis requires exclusion of other explanations for spontaneous hemothorax, including metastatic carcinoma.
Excision of an implicated exostosis may be necessary to avoid recurrences.
