Unsuspected lung cancer accompanied by catamenial pneumothorax.

A 45-year-old nonsmoking woman with repeated coughing and dyspnea on effort was admitted to our hospital diagnosed with right-sided pneumothorax on chest X-ray. Chest computed tomography showed neither bullae nor nodules. Chest drainage failed to completely reexpand the lung, necessitating video-assisted thoracic surgery. Thoracoscopy showed pleural thickening in the apical segment without bullae or air leakage, dark-brown pigmentation of the diaphragm, and an unsuspected small nodule about 5 mm in diameter on the diaphragmatic surface of the right lower lobe. Pneumothorax was treated by mechanical abrasion of parietal pleura and upper lobe wedge resection. The lower lobe and nodule were wedge-resected using staplers. The nodule was bronchioloalveolar carcinoma of Noguchi's type B. To improve curability and check for diaphragmatic lesions, right posterolateral thoracotomy was conducted on post-video-assisted thoracic surgery day 28. Aggressive intraoperative lymph node exploration yielded no remarkable histological findings. Nonanatomical lower lobe wedge resection was done and the diaphragm with pinhole-like perforations was partially resected. The resected lung showed no cancerous tissue. Endometrial tissue was histologically confirmed in the resected diaphragm. The patient has remained asymptomatic in 14-month follow-up. This is, to our knowledge, the first lung cancer accompanied by catamenial pneumothorax.