Which of the following is the hallmark histopathological feature of tuberculosis?
A. Caseating granuloma with central necrosis surrounded by epithelioid histiocytes and Langhans giant cells
B. Suppurative abscess with neutrophilic infiltration and fibrin deposition
C. Non-caseating granuloma with multinucleated giant cells arranged in a palisade pattern
D. Granulomatous inflammation with foamy macrophages and lipid-laden cells
Explanation
Histopathological Features of Tuberculosis
Key Point
The caseating (tuberculous) granuloma is the pathognomonic hallmark of tuberculosis and distinguishes it from other granulomatous diseases.
Structure of Caseating Granuloma
The classic tuberculous granuloma has a characteristic layered architecture:
1.
Central caseous necrosis — acellular, cheese-like debris with fragmented nuclei and cellular remnants
2.
Epithelioid histiocytes — activated macrophages with elongated nuclei arranged in a palisade around the necrotic center
3.
Langhans giant cells — multinucleated giant cells formed by fusion of epithelioid cells, with nuclei arranged in a peripheral horseshoe or crescent pattern
4.
Outer rim of lymphocytes and fibroblasts — chronic inflammatory infiltrate that may undergo fibrosis
High-YieldNEET PG
The presence of caseous (caseating) necrosis is the key distinguishing feature from other granulomatous diseases like sarcoidosis (non-caseating), fungal infections, and foreign body reactions.
While Langhans giant cells are seen in both TB and sarcoidosis, the caseating necrosis is virtually pathognomonic for TB in the appropriate clinical context. Non-caseating granulomas suggest sarcoidosis, fungal disease, or berylliosis.
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