Lobar Pneumonia at 10x Magnification

Pneumonia is a disease characterized by inflammation and congestion of the lungs. Infection with any of a variety of microorganisms is the typical cause, but sometime the condition is related to an allergic reaction or inhalation of fluid, food, or certain gases. When pneumonia is restricted to a single lobe of the lung or to a portion of a lobe, it is referred to as lobar pneumonia. Pneumonia that has more extensively spread through the lungs is known as bronchopneumonia. The Gram-positive bacterium Streptococcus pneumoniae (also called pneumococcus) is responsible for most cases of lobar pneumonia. Other leading causes of the disease include infection withMycoplasma, Legionella, or other Gram-negative organisms.