- Lobar pneumonia
- Bacterial infection of a lung lobe. Classically, there are four stages of inflammation: congestion, red hepatization, gray hepatization, and resolution.
- Congestion
- Vascular engorgement and extensive alveolar edema make the lungs heavy, boggy, and red.
- Red hepatization
- Massive, confluent exudation with RBCs, neutrophils, and fibrin that fills the alveolar spaces. Grossly, the lung looks like liver because it is red, firm, and airless.
- Gray hepatization
- The next phase of lobar pneumonia, where the cut surface of the lung is gray-brown, dry, and granular. Histologically, the alveoli are filled with degenerated RBCs, fibrinous exudate, and degenerating neutrophils.
- Resolution
- The final stage of lobar pneumonia where the semifluid debris in the alveoli is ingested by macrophages, or expectorated. If too much damage has occurred, fibroblasts fill the alveolar spaces with collagen, resulting in a fibrous scar.
- Ground glass opacity
- Hazy areas of increased attenuation in the lung that have preservation of bronchial and vascular markings. It results from either minimal thickening alveolar septae, or the presence of cells or fluid in alveolar spaces. It often indicates the presence of an active and potentially treatable process.
- Endocarditis
- Inflammation of the inside lining of the heart chambers (endocardium) and/or the heart valves.
- Septic emboli
- Emboli consisting of bacteria, fibrin, and neutrophils.
- Aspergilloma
- A clump of aspergillus fungi that grows in a cavity (such as those caused by previous infection with TB). Also called a mycetoma or fungus ball.
- Liquefactive necrosis
- Complete autolysis of necrotic debris resulting in a liquid, viscous mass. Occurs in skin (a.k.a pus) and in the central nervous system (for unknown reasons).
