Inflammation ( part 5) l General pathology revision for dental student
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chronic inflammation
definition :
- inflammatory process in which lymphocytes, plasma cells & macrophages predominate, accompanied by granulation tissue resulting in fibrosis
Cause
- It may follow acute inflammation. (non specific)
- Chronic almost from the onset. (specific)
Types
Chronic non-specific inflammation
- Different irritants can produce this reaction
- The etiological factor can’t be identified e.g. chronic abscess
Chronic specific inflammation(Granuloma)
- Each irritant produces a specific inflammatory reaction
- The etiological factor can be identified from reaction e.g. tuberculosis, bilharziasis
Fate
- Healing with effective treatment.
- Persists, with or without acute exacerbation, and may results in several complications as: chronic toxemia , 2ry amyloidosis, in some sites predispose to neoplasia.
General features
- The irritant is mild and has a prolonged action.
- Onset is gradual and duration is prolonged.
- Initial tissue necrosis may not be marked.
- Vascular phenomenon is less marked than in acute inflammation. Later on, endarteritis obliterans occurs : small arteries show thickening & narrowing by proliferation of sub-intimal CT.
- Fluid exudate is not marked.
- Cellular exudate consists of:
- lymphocytes: main cell of chronic inflammation, change to plasma cell & liberates lymphokines
- Plasma cells: produces antibodies
- Epithelioid cells.
- Giant cells: formed by macrophages fusion.
- The morphology of giant cells is variable. It may be:
- Langhan's giant cell type: when the nuclei are peripherally situated especially in tuberculous lesions.
- Foreign body giant type: when the nuclei are placed centrally as foreign body.
- Reaction Giant cells : have a greater phagocytic power.
- Macrophages: are phagocytic cells widely distributed in tissues and include:
- monocytes of blood
- histiocytes of connective tissue
- Kupffer cells of liver
- littoral cells of spleen and Lymph nodes
- microglia in brain
- osteoclasts of bone.
Their functions are:
- Phagocytosis of necrotic debris.
- Giant cell formation
- Phagocytosis of bacteria and other irritants of chronic Inflammation
- True scavenger cells in repair
- Attempts at repair is seen from the beginning and consists of capillaries and fibroblasts.
GRANULOMAS
Definition:
- Granuloma is a type of chronic specific inflammation characterized by focal accumulation of large number of macrophages together with lymphoeytes, plasma cells, giant cells and fibroblasts forming tiny granules which fuse to form tumour-like masses.
- Macrophages come from outflow of blood monocytes which become immobilized, activated and divide by the action of lymphokines derived from activated T lymphocytes.
Types:
(1) Infective granuloma:
- Bacterial: e.g. tuberculosis, leprosy and syphilis.
- Parasitic: e.g. bilharziasis and leishmaniasis.
- Fungal: e.g. Madura foot.
(2) Non infective granuloma
(foreign body granuloma):
- Silicosis and asbestosis.
- Foreign body granuloma around foreign bodies as pieces of wood or glass, catgut and tale powder... etc.
(3) Granuloma of unknown cause:
e.g. sarcoidosis and regional enteritis.
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