Catamenial pneumothorax complicated by massive right diaphragmatic hernia with solid organ herniation

Catamenial pneumothorax is an uncommon manifestation of thoracic endometriosis syndrome, usually associated with small right-sided diaphragmatic fenestration. We report an extreme presentation in a woman in her late 40s who developed acute right-sided chest pain one day prior to menstruation. Initial imaging revealed a right pneumothorax, which resolved after intercostal drainage. However, subsequent computed tomography revealed a massive defect in the right hemidiaphragm with herniation of the entire right hepatic lobe, gallbladder, and upper pole of the right kidney into the thoracic cavity. A multidisciplinary surgical strategy was adopted, involving abdominal reduction of the herniated viscera, followed by video-assisted thoracoscopic mesh repair of the diaphragm and talc pleurodesis. Postoperative hormonal suppression was initiated. The patient remained asymptomatic without recurrence at 18 months. This case highlights that catamenial pneumothorax may represent advanced chronic diaphragmatic pathology, even at the first clinical presentation.