Factors favouring resolution
- Minimal cell death and tissue damage
- Occurrence in an organ or tissue with regenerative capacity eg liver
- Rapid destruction of the casual agent
- Rapid removal of fluid and debris by good local vascular drainage
organisation
Replacement of destroyed tissue by granulation tissue
Factors favouring organisation
- Large amounts of fibrin
- Substantial necrosis
- Exudate and debris cannot be removed or discharged
Signs of organisation
Signs of organisation
- Sprouting capillaries – production of new capillaries
- Proliferation of fibroblasts
- Macrophage infiltration – inflammatory cell
- New capillary beds
Organisation - granulation tissue
Orgnisation – granulation tissue
- Much skin is completely destroyed and the underlying tissue is undergoing repair. The underlying tissue is undergoing repair, The damaged area is being replaced by vascular granulation tissue.
Inflammatory exudate replaced by
capillaries, macrophages,fibroblasts, collagen
what drives organisation ?
TNF, EGF,FGF - growth factors
Chronic inflammation
- Primary – occur entirely without a previous episode
- Progression from acute inflammation
- Recurrent episodes of acute inflammation
Examples
- Resistance of infective agent to phagocytosis and intracellular eg TB, leprosy, viral infections
- Foreign body reactions to endogenous materials eg gout ( may be acute or chronic )
- Foreign body reactions to exogenous materials eg asbestos
- Some autoimmune diseases such as rheumatoid arthritis – primarily in the synovial of the joints
- Specific diseases of unkown aetiology eg ulcerative colitis
- Primary granulomatous diseases eg sarcoidosis
Factors favouring progression from acute to chronic
- Indigestible substances eg glass, suture material ( foreign body reaction )
- Deep seated suppurative inflammation where drainage is delayed or inadequate
- Thick abcess walls
- Formation of granulation/fibrous tissue
- Pus becomes organised
- Forms fibrous scar
Osteomyelitis – a chronic abcess which is extremely difficult to eradicate
- Recurrent episodes of acut inflammation and healing may eventually result in the clinicopathological entity of chronic inflammation
Chronic cholecystitis – replacement of wall by fibrous tissue lymphocytes rather than neutrophils predominate
What does chronic inflammation look like?
Chronic ulcer
- Mucose breached
- Base lined by granulation tissue
- Fibrous tissue throughout muscle laeyers ( in peptic ulcer)
Chronic abscess cavity eg osteomyelitis, empyema thoracis
Thickening of the wall of a hollow viscus
Granulolmatous inflammation eg tuberculosis
Fibrosis
The cells of chronic inflammation
- On inflammatory process in which lymphocytes plasma cells and macrophages predominate
- Usually accompanied by the formation of granulation tissue resulting in fibrosis
Macrophages
- Considerate phagocytic capabilities
- Can ingest a wide range of materials
- Relatively large cells
- Can harbour viable organisms resistant to lyosomal enzymes eg mycobacterium tuberculosis, mycobacterium leprae
- Produce a range of important cytokines
- Activated on migration to an area of inflammation
- Macrophage activation factor ( MAF )
- Migration inhibition factor ( MIF )
Sarcoidosis in liver – granuloma of epitheloid histiocyte
Granulomatous inflammation
- A granuloma is an aggregate of epitheloid macrophages
- A histriocyte is a a macrophage in connective tissue
- Little phagocytic activity
- Secretory function
- Typical granuloma
- central giant cells +/- caesation
- Surrounded by epitheliod histiocytes
- Peripheral rim of actvivated lymphocytes
Causes of granulomatous disease
- Specific infections
- Foreign bodies – endogenous and exogenous
- Specific chemicals
- Drugs
- Unkown
Granulation inflamamtion
May develop – necrotic tissue, giant cells
Mau causative agents are2 ingestible – foreign bodies, specific infections
Terms to know relating to inflammation
Granuloma - aggregate of macrophage like cells
Granulation - important healing process with small blood vessels and connective tissues
Fibrin - deposited in acute inflammation
fibrous - typical scar tissue with collagen
Acute vs chronic - distinguished by dynamics and character of process, ie time of onset , resolution and cells involved.
Exudate vs transudate - high protein content from inc vasc perm vs low protein content from normal vasc perm
