Bronchiolitis obliterans-organizing pneumonia (BOOP) in children with malignant disease.

Four patients who had completed chemotherapy for malignant disease are presented. Unexpected findings of pulmonary infiltrates on chest radiographs of two patients and solitary and/or confluent nodules on CT in all four led to open lung biopsy. Histologic diagnosis in each case was bronchiolitis obliterans-organizing pneumonia (BOOP). This usually innocuous disorder can be differentiated histologically from the more severe pure bronchiolitis obliterans and should be considered in the differential diagnosis of pulmonary lesions associated with malignant disease.