## Distinguishing Chronic Granulomatous from Chronic Suppurative Inflammation ### Key Histological Difference **Key Point:** Epithelioid macrophages and multinucleated giant cells (Langhans or foreign body type) are the hallmark of granulomatous inflammation and definitively distinguish it from suppurative inflammation. ### Comparative Table | Feature | Granulomatous | Suppurative | | --- | --- | --- | | **Dominant cell** | Epithelioid macrophages, giant cells | Neutrophils, pus formation | | **Microabscesses** | Absent or minimal | Present (hallmark) | | **Causes** | TB, sarcoidosis, fungal infections, foreign body | Bacterial infections (S. aureus, Streptococcus) | | **Duration** | Chronic (weeks to months) | Acute to subacute | | **Fibrosis** | Marked, central caseous necrosis in TB | Variable, minimal in acute phase | | **Plasma cells** | Present but not dominant | Present in chronic phase | ### Why Epithelioid Cells & Giant Cells? 1. **Epithelioid macrophages** arise from activated macrophages that fuse and lose phagocytic capacity 2. **Multinucleated giant cells** form by fusion of epithelioid cells — pathognomonic for granulomatous inflammation 3. These are **absent** in suppurative inflammation, where neutrophilic pus is the defining feature **High-Yield:** The presence of granulomas (epithelioid cells + giant cells) on histology immediately rules out simple suppurative inflammation and prompts investigation for TB, sarcoidosis, or fungal disease. ### Clinical Pearl When you see a biopsy report mentioning "epithelioid granulomas," think: TB, sarcoidosis, fungal infection, or foreign body reaction — NOT acute bacterial abscess. ### Mnemonic **GRANULOMA = GRAnular + NUcleated + LOng-standing MAcrophages**
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