Catamenial Pneumothorax in a Patient Undergoing Low-Dose Estrogen-Progestin Therapy: A Case Report.

A 46-year-old woman on low-dose estrogen-progestin (LEP) therapy for endometriosis developed a right-sided pneumothorax. Surgical findings included a pulmonary bulla in the right middle lung lobe and a small hole in the center tendon of the diaphragm, both of which were partially resected. Histopathology confirmed the presence of endometrial tissue, leading to a diagnosis of thoracic endometriosis. This case demonstrates that catamenial pneumothorax can occur despite LEP therapy, which is intended to suppress endogenous hormones. Clinicians should remain vigilant for this condition in patients with a history of endometriosis, even when hormonal treatment is in use.