Pathophysiology of Inflammation

1. Inflammation

92. TYPES OF CHRONIC INFLAMMATION
Descriptive classification, histological features are used for classifying
chronic inflammation into 2 corresponding types:
1. 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.
2. Chronic granulomatous inflammation. It is characterised by
formation of granulomas e.g. tuberculosis, leprosy, syphilis,
actinomycosis, sarcoidosis etc.

93. 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.

94. PATHOGENESIS OF GRANULOMA
• The sequence in evolution of granuloma briefly outlined below:
1. Engulfment by macrophages
2. CD4+ T cells
3. Cytokines

95. COMPOSITION OF GRANULOMA
In general, a granuloma has the following structural composition:
1. 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.
2. 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.

96. 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…

97. Wound Healing