A case of multiple pulmonary adenocarcinoma concealed by giant thymic cyst

A 69-year-old woman treated for an asthma attack elsewhere, was incidentally pointed out as showing an abnormal chest shadow. Chest computed tomography (CT) showed a nodule in the right upper lobe and atelectasis of the middle lobe associated with pleural effusion. She was referred to our hospital for further examination. After pleural drainage, re-expansion of the middle lobe was obtained with improvement of pulmonary function, and new nodules in the middle and the right lower lobe were pointed out. Video-assisted middle lobectomy and partial resection of the upper and lower lobes were performed. Unexpectedly, the cause of atelectasis was a giant thymic cyst and not pleural effusion. The histopathological diagnosis based on all pulmonary lesions was bronchioloalveolar carcinoma, Noguchi's type B, and the cyst was lined with monolayered columnar epithelium containing adipose tissue with a thymic gland in the wall. The patient is currently free of disease at 30 months postoperatively. We herein report a case of synchronal multiple pulmonary adenocarcinoma concealed by a giant thymic cyst.