A 40-year-old woman with leukemia is treated with chemotherapy. During treatment she develops increasing cough and shoness of breath. A chest X-ray shows diffuse lung infiltrates. Sputum cultures are negative and the patient does not respond to routine antibiotic therapy. An open lung biopsy is diagnosed by the pathologist as viral pneumonia. Which of the following histopathologic findings would be expected in the lungs of this patient?