Inflammation is a response to a noxious stimuli which can be either be acute or chronic.
The cardinal signs of inflammation include:
- loss of tissue function
Acute inflammation occurs within the first few hours after an injury.
In acute inflammation there are vascular and exudative phases.
- vascular: dilatation and increased permeability
- exudative: fluid and cells escape from permeable venules
The outcome of acute inflammation can be:
- resolution (restoration of normal function)
- non resolution
- organisation (scarring)
- progression to chronic inflammation
Chronic inflammation occurs when there is a persistent damaging stimulus. This eventually heals by either scarring or granuloma formation.
Chronic inflammation differs from acute inflammation as it can last for a much longer period of time i.e. from months to years.
Chronic inflammation is characterised by infiltration with mononuclear cells (macrophages, lymphocytes).
Outcomes of chronic inflammation include:
- a continuing response to persisting inflammatory triggers, such as infectious agents, autoimmune products, and immune complexes.
- the inflammatory cells including lymphocytes and macrophages will either be cleared or remain at the site.
- the development of giant cells along with fibrosis and/or necrosis.
Granulomatous inflammation is specific subtype of chronic inflammation charcterised by aggregation of epitheliod histiocytes. Examples of Type IV hypersensitivity reaction include:
- infections (tuberculosis)
- foreign bodies
- idiopathic (eg. sarcoid)
- 1. Kumar, V; Cotran, R.S., Robbins, S.L. Robbins Basic Pathology, 7th edition
- 2. Serhan C, Ward P, Gilroy D, Ayoub S. Fundamentals of Inflammation. Cambridge: Cambridge University Press; 2010.