病毒性肺炎间质淋巴细胞浸润。没有肺泡腔渗出物。因此，很少咳嗽。病毒性肺炎最常见的病原是流感病毒，副流感病毒，腺病毒，以及呼吸道合胞体病毒( RSV 主要发生于儿童)。巨细胞病毒则发生在免疫缺乏病人。
Here is the microscopic appearance of a viral pneumonia with interstitial lymphocytic infiltrates. Note that there is no alveolar exudate. Thus, the patient with this type of pneumonia will probably not have a productive cough. The most common causes for viral pneumonia are influenza, parainfluenza, adenovirus, and respiratory syncytial virus (RSV appears mostly in children). Cytomegalovirus can appear in immunocompromised hosts.