[Early stage pulmonary alveolar proteinosis detected by chest CT scan in a medical examination].

We report a case of pulmonary proteinosis detected at an early stage and followed up on chest CT. A 49-year-old man underwent detailed examinations because of abnormal shadows on chest CT taken on a routine medical examination. The chest CT revealed almost symmetrical ground glass opacities (GGOs) in both lungs with thickened alveolar septa. We could not make a definitive diagnosis even with bronchoalveolar lavage and transbronchial lung biopsy, but after about half a year, the GGOs increased. VATS-biopsy demonstrated alveoli filled with PAS-positive granular materials, and we made a diagnosis of pulmonary alveolar proteinosis. This case was found at an early stage and we were then able to follow up the disease.