[A case of pulmonary alveolar proteinosis that showed solitary ground-glass opacity in the subpleural area].

A 58-year-old man visited our department regarding a growing ground-glass opacity (GGO) on chest CT. He underwent video-assisted thoracic surgery, because a malignancy such as bronchioloalveolar adenocarcinoma was suspected. However, histopathologic examination revealed pulmonary alveolar proteinosis (PAP). A chest X-ray film of PAP usually shows bilateral interstitial and/or alveolar shadows in a "butterfly pattern", while chest CT usually shows thickened interlobular septa and intralobular structures, referred to as a "crazy-paving appearance". The present case presented solitary localized GGO growing in a subpleural area which was thought to be a rare type of early PAP.