Catamenial pneumothorax and endometriosis: Report of a rare case

Introduction: Catamenial pneumothorax is a rare condition which is characterized by the recurrent accumulation of air within the pleural cavity without related respiratory diseases. It happens in women of reproductive age, usually within 72 hours before or after onset of menstruation. It occurs in association with characteristic pleural lesions, right-sided location of the pneumothorax, and concomitant thoracic endometriosis. The objective is to report a rare case of thoracic endometriosis in a 35-year-old woman with recurrent catamenial pneumothorax. Case Report: A 35-year-old female presented with persistent and recurrent right pneumothorax usually occurring immediately after her menstruation. She had no personal history of lung problems, asthma, bronchitis, or any family history of any chronic lung disease. Computed tomography (CT) of the chest showed a large hydropneumothorax on the right side resulting in near-complete collapse of the right lung and mediastinal shift from right to left. The gross specimen comprised the right upper lobe resection of the lung, which weighed 4.9 grams and measured 7.7 cm × 1.5 cm × 1.2 cm. The pleura was mottled brown-gray with adhesions. Histopathologic findings showed pleural endometriosis (pleural endometrial glands and stroma present), consistent with catamenial pneumothorax. Associated pleural adhesions with acute and chronic inflammation and mild emphysematous changes in the lung parenchyma were also noted. Immunohistochemistry with immunostains estrogen receptor (ER) and CD10 highlighted the endometrial glands and stroma which confirmed the diagnosis. Conclusion: There should be a high index of suspicion of catamenial pneumothorax in women of reproductive age who present with pneumothorax during the perimenstrual period. Adequate sampling of lung wedge resections and careful microscopic examination, followed by confirmation with immunohistochemistry, play important roles in the diagnosis of this rare condition.