Thoracic endometriosis presenting with bilateral haemothoraces: a rare but important cause of bilateral pleural effusions.

A woman in her 30s was admitted with 6 months of progressive shortness of breath and cyclical bilateral pleuritic chest pain associated with heavy, painful menstruation. She had a history of endometriosis. Chest X-ray revealed a large right pleural effusion requiring several aspirations. The pleural aspirate was haemorrhagic. Cytology revealed no malignant cells. CT thorax-abdomen-pelvis did not reveal any lung masses or pleural abnormalities. Pelvic MRI showed multiple uterine fibroids and a few simple left ovarian cysts. She re-presented a few months later with bilateral effusions, worse on the right than the left. The right required an intercostal drain. The left pleural aspirate was haemorrhagic, and cytology was the same as the right. She underwent right video-assisted thoracoscopic surgery directed pleural biopsies and diaphragmatic excision. Histology revealed endometrial tissue, confirming thoracic endometriosis. She was started on oral contraception, leading to resolution of the effusions.