[A case of migratory air space infiltration after radiation therapy for breast cancer].

A 54-year-old woman underwent conserving surgery for right breast cancer, and received a cumulative dose of 50 Gy of radiation therapy to the remaining part of the right breast. About five months after the termination of irradiation, cough and low-grade fever developed. The chest radiograph showed an infiltrative shadow in the right lung field. Organizing pneumonia was identified in the transbronchial lung biopsy specimen. After prednisolone was given to the patient the clinical symptoms and infiltrates seen in the radiograph disappeared. In the course of tapering the prednisolone dose, new infiltrative shadows developed in the upper right lung and the left lung. The histologic changes were shown by transbronchial lung biopsy to be organizing pneumonia. The increased dose of prednisolone resulted in the rapid improvement of the clinical symptoms and chest radiograph abnormalities. This case suggests that breast radiation after conserving surgery for breast cancer may cause a pathologic process similar to that of bronchiolitis obliterans organizing pneumonia.