A 22-year-old man with a positive tuberculin skin test develops a cavitary lung lesion. Biopsy shows a granuloma with central amorphous, eosinophilic, necrotic debris. The necrosis is best classified as:
- A Coagulative necrosis
- B Liquefactive necrosis
- C Caseous necrosis ✓
- D Fibrinoid necrosis
Correct answer: C. Caseous necrosis
Explanation
Caseous necrosis is the hallmark of tuberculosis. It appears as amorphous, granular, eosinophilic debris with loss of cellular outlines, driven by a type IV hypersensitivity response. Coagulative necrosis preserves tissue architecture, liquefactive necrosis is seen in abscesses, and fibrinoid necrosis occurs in vessel walls in immune complex disease.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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