An autopsy of a patient who died of disseminated tuberculosis shows a lung lesion with a central zone of amorphous, granular eosinophilic debris in which all cellular outlines and tissue architecture are completely lost. The debris contains fragments of the causative organism and is enclosed by epithelioid cells and Langhans giant cells. Which type of necrosis does this represent?
- A Coagulative necrosis
- B Liquefactive necrosis
- C Caseous necrosis ✓
- D Fibrinoid necrosis
Correct answer: C. Caseous necrosis
Explanation
Caseous necrosis is the hallmark of tuberculous infection. It combines features of coagulative and liquefactive necrosis: the tissue is converted to amorphous granular debris that retains no cellular outlines or architecture, unlike coagulative necrosis where ghost outlines persist for days. The name comes from its gross cheese-like appearance. Liquefactive necrosis produces fully liquid pus-like material, typical of brain infarcts and pyogenic abscesses, not granulomas.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
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