Pathophysiology of Inflammation

Pathophysiology of Inflammation

1. Inflammation

2. TYPES OF CHRONIC INFLAMMATION D escriptive classification, histological features are used for classifying chronic inflammation into 2 corresponding types: Chronic non-specific inflammation . It is characterised by non-specific inflammatory cell infiltration e.g. chronic osteomyelitis, lung abscess. A variant of this type of chronic inflammatory response is chronic supportive inflammation in which infiltration by polymorphs and abscess formation are additional features e.g. actinomycosis. Chronic granulomatous inflammation . It is characterised by formation of granulomas e.g. tuberculosis, leprosy, syphilis, actinomycosis, sarcoidosis etc.

3. GRANULOMATOUS INFLAMMATION The word ‘granuloma’ is derived from granule meaning circumscribed granule-like lesion, and - oma which is a suffix commonly used for true tumours but here it indicates a localised inflammatory mass or collection of macrophages. Granuloma is defined as a circumscribed, tiny lesion, about 1 mm in diameter, composed predominantly of collection of modified macrophages called epithelioid cells, and rimmed at the periphery by lymphoid cells.

4. PATHOGENESIS OF GRANULOMA The sequence in evolution of granuloma briefly outlined below: Engulfment by macrophages CD4+ T cells Cytokines

5. COMPOSITION OF GRANULOMA In general, a granuloma has the following structural composition: Epithelioid cells . These are so called because of their epithelial cell-like appearance, are modified macrophages/ histiocytes which are somewhat elongated, having vesicular and lightly-staining slipper-shaped nucleus, and pale. Epithelioid cells are weakly phagocytic. Multinucleate giant cells . Multinucleate giant cells are formed by fusion of adjacent epithelioid cells and may have 20 or more nuclei. The former are commonly seen in tuberculosis while the latter are common in foreign body tissue reactions. Like epithelioid cells, these giant cells are weakly phagocytic but produce secretory products which help in removing the invading agents.

6. 3. Lymphoid cells . As a cell mediated immune reaction to antigen, the host response by lymphocytes is integral to composition of a granuloma. 4 . Necrosis. Necrosis may be a feature of some granulomatous conditions e.g. central caseation necrosis of tuberculosis, so called because of cheese-like appearance and consistency of necrosis. 5. Fibrosis . Fibrosis is a feature of healing by proliferating fibroblasts at the periphery of granuloma. EXAMPLES: Tuberculosis Leprosy Syphilis Actinomycosis etc…

7. Wound Healing