B. Tuberculosis lung

B. Tuberculosis lung:

Primary tuberculosis occurs in individuals infected with mycobacterium tuberculosis for the first time and lung is the most common site of involvement. Secondary tuberculosis occurs in previously sensitized individuals, due to reinfection/reactivation of dormant disease/ progress from primary lesion.

Gross:

1. Specimen of lung with a cavitory lesion in the upper part of lung

2. Cut surface shows irregular areas of fibrocaseous necrosis

Microscopy

Tuberculosis Lung.png

Section of lung with alveoli and anthracotic pigment
Granuloma consisting of central caseating necrosis surrounded by epithelioid cells, Langhan’s giant cells and rim of lymphocytes seen in the inter alveolar spaces.

Diagnosis

Tuberculosis lung

Key Questions & Answers

1. What are the gross features of the specimen?

Ans: Cut section of a specimen of lung showing cavitory lesion at the apex and many foci of grey white caseous necrotic areas.

2. What are the microscopic features?

Ans: Sections show alveoli and many granulomas composed of caseous necrosis, surrounded by collection of epithelioid cells, Langhans giant cells and lymphocytes in the inter alveolar space.

3.Name the primary sites of above condition

Ans: Lung, Tonsils, Intestine, Skin and eye.

4.Name the atypical bacteria of this condition

Ans: Mycobacterium avium

Mycobacterium intracellulare.

5.What is the type of hypersensitivity reaction associated with this disease?

Ans: Cell mediated (type IV) hypersensitivity reaction.

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