Catamenial pneumothorax: a rare manifestation of endometriosis.

Endometriosis is a common gynecological disease that primarily affects premenopausal women. It is mainly found in the pelvis but may be found at several extrapelvic locations. Thoracic endometriosis is a rare extrapelvic location of endometriosis and the leading cause of catamenial pneumothorax. We describe the case of a 35-year-old woman with a background of pelvic pain presenting to the emergency department with chest pain and dyspnea. The chest X-ray in the emergency department showed a large right-sided pneumothorax. Further imaging studies during patient evaluation revealed extensive fibrotic changes in the pelvis and well-defined solid nodules with high signal on T2 and T1-weighted images on MRI in abdominal and thoracic locations, rendering the diagnosis of a catamenial pneumothorax in a patient with pelvic, abdominal and thoracic endometriosis.