[Catamenial pneumothorax]

Including the case herein recorded, 33 cases of spontaneous pneumothorax occurring concurrently with menses (catamenial pneumothorax) have now been reported. The pathogenesis of the pneumothorax is not understood; it appears to occur exclusively on the right side. In 27 patients who underwent exploratory right thoracotomy, pleural or diaphragmatic endometriosis was found in 8 cases. 11 patients had clinical or histologic evidence of pelvic endometriosis.