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Tuberculosis
Tuberculosis
A chronic granulomatous inflammation caused by Koch’s bacilli - Mycobacterium tuberculosis.
The species M Tuberculosis Hominis is transmitted by inhalation of infective droplets and it mainly involves the Lungs, while M Tuberculosis Bovis is transmitted by milk from diseased cows and results in primary tuberculosis of intestines / tonsils
Gross
Gross
1. Enlarged, matted group of lymph nodes
2. Cut surface shows tan white cheesy areas of caseation
Microscopy:
Microscopy:
Caseous necrosis.png
Structure of lymph node with multiple granulomas.
The granulomas are composed of central area of caseation, surrounded by epithelioid cells, Langhan’s giant cells and lymphocytes.
The epithelioid cells have plump oval to slipper shaped vesicular nuclei with irregularly clumped chromatin.
Diagnosis
Diagnosis
Tubercular lymphadenitis
Key Questions & Answers
Key Questions & Answers
1. Define chronic inflammation.
It is an inflammation of prolonged duration with coexistence of tissue injury and attempts of repair. It may follow either an acute inflammation or may begin insidiously as a low-grade, smouldering response resulting in tissue damage.
2. What is a granuloma?
It is a collection of epithelioid cells, the modified macrophages formed due to the presence of poorly digestible irritant &/or T cell mediated immunity to the irritant
3. Describe an epithelioid cell.
Epithelioid cells are activated macrophages resembling epithelial cells. They have indistinct cell margins, pale eosinophilic granular cytoplasm, central elongated/ slipper shaped vesicular nucleus with irregularly clumped chromatin.
4. Describe the pathogenesis of granulomatous inflammation
It is a specific form of chronic inflammation initiated by – infectious/ non infectious agents resulting in formation of a Granuloma. The formation of granuloma requires – presence of poorly digestible irritant &/or T cell mediated immunity to the irritant.
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