Catamenial pneumothorax caused by endometriosis in the visceral pleura

Catamenial pneumothorax is a rare clinical entity of unknown etiology. The most well known hypothesis is passage of air from the genital tract through endometrial fenestrations in the diaphragm. Although some reports are associated with diaphragmatic endometriosis, few have been confirmed endometrial implants in the visceral pleura. We describe a very rare case of catamenial pneumothorax caused by ectopic endometriosis in the visceral pleura confirmed histopathologically in a woman 1-year after hysterectomy.