Acute respiratory illness in children with acute lymphoblastic leukemia.

Ten of 70 children (14%) with acute lymphoblastic leukemia developed severe interstitial pneumonitis within three weeks after induction of central nervous system prophylactic therapy. The clinical picture was characterized by fever, cough, progressive dyspnea, and hypoxemia with complete resolution in one to three weeks, except in one patient who died during the acute illness from respiratory failure. P. carinii organisms were found in the lung tissue of only one patient. The etiology of the pneumonitis in the other nine children was probably viral, acquired or activated during a period of lymphopenia and immunosuppression. The morbidity and potential mortality from the pneumonitis warrants early recognition by open lung biopsy and intensive supportive therapy.