MIGRATORY ORGANIZING PNEUMONITIS PRIMED BY RADIATION-THERAPY

We report on two women presenting with cough and fever, 4 and 7 months , respectively, after starting breast radiation therapy following surg ery for breast carcinoma. Chest roentgenogram and computed tomographic (CT) scan demonstrated alveolar opacities, initially limited to the p ulmonary area next to the irradiated breast, but later migrating withi n both lungs. Intra-alveolar granulation tissue was found in transbron chial lung biopsies. Corticosteroid treatment resulted in dramatic cli nical improvement, together with complete clearing of the pulmonary op acities on chest imaging. However, clinical and imaging relapses occur red when corticosteroids were withdrawn too rapidly; with further impr ovement when they were reintroduced. The reported cases clearly differ from radiation pneumonitis. They were fairly typical of cryptogenic o rganizing pneumonitis, also called idiopathic bronchiolitis obliterans organizing pneumonia, with the exception of the radiation therapy, pa rtially affecting the lung, which had been performed within the previo us months. Since focal radiation therapy involving the lung may induce diffuse bilateral lymphocytic alveolitis, we hypothesize that this ma y ''prime'' the lung to further injury, leading to cryptogenic organiz ing pneumonitis.