A patient dies 4 days after an acute anterior STEMI. At autopsy, a pericardial friction rub had been heard on day 2. Microscopic examination of the infarct zone at this stage would most likely show:
- A Dense macrophage infiltration with removal of necrotic debris (myophagocytosis)
- B Neutrophilic infiltration with coagulative necrosis and loss of nuclear staining ✓
- C Early granulation tissue with angiogenesis and fibroblast proliferation
- D Dense collagen scar with complete replacement of myocardium
Explanation
The temporal sequence of histological changes in MI is predictable: within 12-24 hours — coagulative necrosis with eosinophilic bands and loss of nuclei/cross-striations, wavy fibres at the periphery. By 1-3 days — neutrophilic infiltration peaks, with coagulative necrosis showing hypereosinophilic 'ghost cells'. By 4-7 days — macrophage infiltration begins, removing necrotic debris. By 10-14 days — granulation tissue with angiogenesis. By 6-8 weeks — collagen scar maturation. At day 4, the dominant picture is neutrophilic infiltration with ongoing coagulative necrosis. Pericarditis at day 2 is epistenocardiac pericarditis, which is distinct from Dressler syndrome (autoimmune pericarditis at weeks). Macrophage dominance, granulation tissue, and scar formation occur in subsequent phases.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.