\s=b\A rapidly progressive, fatal pneumonia occurred during the third week of hospitalization in an immunosuppressed man confined in a laminar airflow room. Respiratory syncytial virus was isolated from open lung biopsy tissue. Epidemiologic data suggested that the virus was community acquired. Respiratory syncytial virus should be considered in the differential diagnosis of pneumonia in severely immunocompromised adults. (JAMA 1981;246:366-368) RESPIRATORY syncytial virus (RSV) is an important lower respira¬ tory tract pathogen of infants and young children and may be a major cause of fatal pneumonia during the first year of life.' In the past, adult disease has been said to be mild, producing an illness like the common cold.' Recently, observations suggest that adult RSV infection can be pro¬ longed and severe, resembling influ¬ enza.2,3 Although a few cases of pneu¬ monia have occurred, mortality in adults, to our knowledge, has not been described.4,5 This article reports a fatal case of RSV pneumonia in a severely immunocompromised man. Although his pneumonia first ap¬ peared during the third week in the hospital, a serological and retrospec¬ tive symptom-survey of his household and hospital contacts suggested com¬ munity acquisition. Patient and Methods A 44-year-old salesman was admitted to the Protected Environment Unit of Har¬ per Hospital in March 1979 for induction chemotherapy of acute myelogenous leuke¬ mia.Three years earlier, he had been treated with combined-modality therapy for stage IIIA-2 Hodgkin's lymphoma, mixed cellu-larity subtype. Radiation treatment and chemotherapy were discontinued when pancytopenia with hypocellular marrow occurred. In January 1979, myeloblasts appeared in his peripheral blood smear. Results of bone marrow aspiration were compatible with acute myelogenous leuke¬ mia.Four days before admission, the patient had daily temperature elevations to 38.9°C , sweats, epistaxis, and severe pain and swelling of the right ear. Other than an anaphylactic reaction to penicillin, his history was unremarkable.The patient was a pale, diaphoretic, acutely ill man. His temperature was 38.9°C. His right external ear and canal were edematous, painful, and red. The tympanic membrane could not be seen. Results of physical examination were unremarkable. His hemoglobin level was 7.5 g/dL; plate¬ let count, 47,000/cu mm; WBC count, 29,000/cu mm, with 880 polymorphonuclear cells per cubic millimeter and 14,660 myeloblasts per cubic millimeter. Serum levels of IgG, IgA, and IgM were normal. Thirty-six percent of his peripheral lym¬ phocytes formed rosettes with unsensitized sheep RBCs (normal, 41% to 81%), and 23% carried IgM surface immunoglobulin. One-way mixed lymphocyte cul¬ tures harvested at five days, using unre¬ lated lymphocytes as stimulating cells, showed a stimulating index of 1:1; in contrast, the reverse stimulating index was 128:1. A Gram's stain of the ear canal exúdate showed rare WBCs and Gramnegative rods, and clusters of Grampositive cocci; culture yielded Staphylococcus aureus....