A 15-year-old asymptomatic girl had an abnormal shadow pointed out on a chest roentgenogram during a school medical health check. Her chest X-ray films showed a mass in the left pulmonary hilum that had increased in size during the past 2 years. Chest computed tomography (CT) showed a mass, which showed slight accumulation on FDG-PET in the left pulmonary hilum. Left lower lobectomy was performed for diagnosis, and the histopathological diagnosis was hyaline vascular-type Castleman disease. We report a case of hyaline vascular-type Castleman disease in the right pulmonary hilum which increased quite rapidly.