The incidence of symptomatic pneumonitis in patients who had received radiation therapy for breast cancer is low (<1%). Recently, bronchiolitis obliterans organizing pneumonia (BOOP) syndrome has been described as a secondary lung toxicity due to the radiation therapy, which appears beyond the radiation field (migratory pneumonitis) and is triggered by hypersensitivity reactions mediated by eosinophils, neutrophils and lymphocytes.
We present a patient who, two months after concluding the scheduled radiotherapy, developed a set of clinical, pathological and radiological symptoms compatible with BOOP syndrome. The patient responded well to steroid treatment.