An abscess is a collection of pus collected in a cavity formed by the tissue on the basis of an infectious process (usually caused by bacteria or parasites) or other foreign materials (e.g. splinters or bullet wounds). It is a defensive reaction of the tissue to prevent the spread of infectious materials to other parts of the body.
The organisms or foreign materials that gain access to a part of tissue kill the local cells, release toxins and trigger an inflammatory response by drawing huge amounts of white blood cells to the area and increasing the regional blood flow. So, pus is a collection of local dead tissue cells, white blood cells, infecting organisms or foreign material and toxins released by both organisms and blood cells. The final structure of the abscess is an abscess wall that is formed by the adjacent healthy cells in an attempt to build a barrier around the pus that limits the infected material from neighboring structures.

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Meta Description: [ An abscess is a tender, easily pressed mass generally surrounded by a colored area from pink to deep red. The middle of an abscess is full of pus and debris. ... ]
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| Histopathology Lung --Bronchopneumonia with micro-abscesses |