All of the following features are seen in the viral pneumonia except -

Ref: Textbook of pathology (Harsh Mohan) 6th edition, page No.473 Histologically, hallmark of viral pneumonias is the interstitial nature of the inflammatory reaction. The microscopic features are as under i) Interstitial inflammation: There is thickening of alveolar walls due to congestion, oedema and mononuclear inflammatory infiltrate comprised by lymphocytes, macrophages and some plasma cells. ii) Necrotising bronchiolitis: This is characterised by foci of necrosis of the bronchiolar epithelium, inspissated secretions in the lumina and mononuclear infiltrate in the walls and lumina. iii) Reactive changes: The lining epithelial cells of the bronchioles and alveoli proliferate in the presence of virus and may form multinucleate giant cells and syncytia in the bronchiolar and alveolar walls. Occasionally, viral inclusions (intranuclear and/or intracytoplasmic) are found, especially in pneumonitis caused by CMV. iv) Alveolar changes: In severe cases, the alveolar lumina may contain oedema fluid, fibrin, scanty inflammatory exudate and coating of alveolar walls by pink, hyaline membrane similar to the one seen in respiratory distress syndrome . Alveolar changes are prominent if bacterial infection supervenes.