Diffuse pulmonary uptake of indium-111-labeled leukocytes in drug-induced pneumonitis

Indium-111-labeled-leukocyte scintigraphy was performed on three febrile patients, two of whom had no signs or symptoms referable to the respiratory tract. The third patient had dyspnea on exertion, unchanged over two months. Their past histories were remarkable in that all three had recently undergone chemotherapy for malignancy (2 lymphoma, 1 malignant thymoma). Diffuse pulmonary uptake of labeled leukocytes was observed in all three individuals. As a direct result of leukocyte imaging, all three underwent fiberoptic bronchoscopy and transbronchial biopsy. The final diagnosis in each of these patients was drug-induced pneumonitis, which responded to treatment with corticosteroids. This entity should be added to the group of conditions, both infectious and noninfectious, that cause diffuse pulmonary uptake on labeled leukocyte images. Moreover, in the appropriate clinical setting, even in the absence of pulmonary signs or symptoms, diffuse pulmonary uptake of labeled leukocytes should alert the physician to the possibility of drug-induced pneumonitis.