The Macroscopic study
Distribution and location of the lesions
- Focal: the lesion corresponds to a focus or specific area of the parenchyma. E.g.: hepatic abscess
- Focally extensive: affects a single area of the organ, but is extensive. E.g.: typically corresponds to pneumonic processes such as catarrhal bronchopneumonia.
- Multifocal: multiple foci of the organ of irregular and random distribution. E.g.: in the course of rumen lactic acidosis it can lead to foci of necrosis in the liver of a calf, the process corresponding to a multifocal hepatic necrosis (hepatic necrobacillosis). When the lesions are very numerous the foci can tend to confluence giving a slightly different image. This distribution process is called multifocal to coalescent, e.g. pulmonary tuberculosis.
- Diffuse: it affects the whole parenchyma of the organ. E.g.: hepatic fatty degeneration.
Occasionally other terms may be used, depending on the type of organ:
- Unilateral/bilateral: in paired organs, to indicate that it affects one or both.
- Transmural: for tubular organs when the lesion affects the entire wall of the organ.
An approximate objective size should be given by measuring the lesions or by referring to an object, such as a scalpel blade. The size is always in relation to the size of the animal. For example, in small animals the presence of blunt edges and compact liver is significant of organ enlargement - hepatomegaly.
Primary colors should be used (black, brown, gray, green, red, yellow). Coloration may be increased or decreased. Avoid other adjectives as descriptors: salmon color, cherry red, etc.
Common descriptions: elongated, circular, oval, wedge-shaped, clustered (very numerous lesions similar to a bunch of grapes), polypoid or if difficult to determine may include that the lesion is irregularly shaped.
It is recommended to use understandable descriptions: smooth, shiny, rough or rough, concave or convex, wavy, cobblestone, crusted, plaque-like, eroded, ulcerated, umbilicated, warty appearance, etc.
The margins are generally described as well or poorly demarcated; but other adjectives such as smooth, indurated, protruding, etc. can also be included.
The consistency can be firm (as in the case of normal liver), soft, hard (bone tissue), fluid, viscous, caseous (example of tuberculous granulomas), sandy, spongy, rubbery, elastic or friable (example of liver with fatty degeneration).