A case of bronchiolitis obliterans organizing pneumonia syndrome with preceding radiation pneumonitis after breast-conserving therapy.

Recent case series have demonstrated that bronchiolitis obliterans organizing pneumonia (BOOP) after radiation therapy to the breast is a distinct clinicopathological entity. Most of the investigators speculated that radiation may prime the development of BOOP through an unidentified immunological process; however, none of them showed the relationship between direct radiation injury and BOOP. We report herein a case of a 67-year-old female with BOOP following direct radiation damage confined to the irradiated area after breast-conserving therapy. This is the first case demonstrating that BOOP after breast-conserving therapy arises from direct radiation injury.