Pneumonitis in acute lymphatic leukemia during methotrexate therapy

Four cases of an acute, self-limited respiratory illness in children who were receiving intermittent methotrexate therapy for the maintenance of remission of acute lymphatic leukemia are described; the description includes clinical and radiographic features, viral and serologic studies, and pulmonary biopsies in two of the patients. The clinical, radiographic, and histologic features were nonspecific. Changing complement fixation titers for respiratory syncytial virus in two patients and pleuropneumonia-like organisms in a third suggested that this syndrome may be caused by an infectious process, modified by the underlying illness or by the antimetabolite therapy.