All of the following are characteristic features of granulomatous inflammation EXCEPT:

Explanation

## Granulomatous Inflammation: Cellular Architecture **Key Point:** Granulomatous inflammation is a chronic inflammatory response characterized by the accumulation of activated macrophages (epithelioid cells) and multinucleated giant cells, NOT neutrophils. ### Correct Cellular Components | Feature | Description | Significance | |---------|-------------|-------------| | Epithelioid histiocytes | Activated macrophages with elongated nuclei | Core of granuloma | | Langhans giant cells | Multinucleated cells with peripherally arranged nuclei | Pathognomonic for TB and sarcoidosis | | Foreign body giant cells | Randomly arranged nuclei | Non-specific granulomas | | Lymphocytes | Surrounding the granuloma | T-cell mediated immunity | | Fibroblasts | Peripheral encapsulation | Chronic phase, fibrosis | **High-Yield:** Neutrophils are characteristic of **acute suppurative inflammation**, not granulomatous inflammation. Granulomatous inflammation is a **chronic hypersensitivity reaction** mediated by Th1 and Th17 cells, resulting in activation of macrophages. ### Why Neutrophils Are Absent 1. Granulomatous inflammation is **cell-mediated** (Type IV hypersensitivity), not antibody-mediated 2. The antigen persists and cannot be easily cleared, leading to chronic activation 3. Macrophages become activated and transform into epithelioid cells 4. Neutrophils are recruited in **acute** inflammation (hours to days), not chronic granulomatous responses (weeks to months) **Clinical Pearl:** When you see a granuloma on histology with abundant neutrophils, suspect **suppurative granuloma** (e.g., cat-scratch disease, tularemia) rather than non-suppurative granuloma (TB, sarcoidosis). **Mnemonic:** GEM = **G**ranuloma has **E**pithelioid cells and **M**acrophages, not neutrophils. [cite:Robbins 10e Ch 3]