[Bronchiolitis obliterans organizing pneumonia (BOOP) in Japan]

Twenty-nine patients with bronchiolitis obliterans organizing pneumonia (BOOP) in Japan diagnosed by an open lung biopsy were reviewed. A total of 70% of the patients were idiopathic and 2/3 of the remaining were associated with connective tissue disease. All 29 cases of BOOP showed bilateral pulmonary infiltration on chest X-rays. BOOP can be classified based on the chest X-ray findings into three major types, Type I, Type II and unclasSified type. In Type I shadows appear in the lung fields. In Type II abnormal shadows are seen in the bi-basilar peripheral field with the reduction of the lung volume. Cases of Type I showed inflammatory findings more frequently than cases of Type II. Among 29 BOOP patients, two idiopathic cases died.