[Pulmonary adenocarcinoma with multiloculated cystic change]

A 63-year-old man was admitted to our hospital for evaluation of an abnormal chest X-ray film finding. He was asymptomatic. The chest HRCT showed a ground-glass attenuation with multiloculated cystic change in the left lower lobe. There were no cystic lesions in the other lung fields except a ground-glass attenuation in the left lower lobe. The pathological examination of trans-bronchial lung biopsy specimen revealed adenocarcinoma. Therefore, primary lung cancer was diagnosed, and he underwent left lower lobectomy and mediastinal lymph node resection. Macroscopic examination of the resected lung specimen revealed multiloculated cystic lesions associated with a poorly demarcated white-gray tumor. The histological examination showed that papillary adenocarcinoma proliferated along the alveolar walls and that the walls of the multiloculated cystic lesions were composed of cancer cells. We speculated that adenocarcinoma cells extended along the alveolar walls and destroyed the alveoli without disrupting the overall lung architecture, resulting in enlarged multiloculated cystic lesions.