Pneumonia

inflammation of the lung parenchyma characterized by consolidation of the affected part, the alveolar air spaces being filled with exudate, inflammatory cells, and fibrin

Description
Most cases of pneumonia are due to infection by bacteria or viruses, a few to inhalation of chemicals or trauma to the chest wall, and a small minority to rickettsiae, fungi, and yeasts. Distribution may be lobar, segmental, or lobular; when lobular and associated with bronchitis, it is termed bronchopneumonia. See pneumonitis