Characteristic feature of viral pneumonias is ?
Interstitial mononuclear infiltration
Intra-alveolar proteinaceous exudate
Hyaline membrane lining alveoli
Fibrotic septa
Ans. is 'a' i.e., Interstitial mononuclear infiltration The predominant histological pattern in case of viral penumonias is the interstitial nature of the inflammatory reaction viually localized within the walls of the alveoli. The infiltrates are usually mononuclear cells such as -lymphocytes, histocytes, plasma cells