During a pathology seminar, the instructor discusses the histological features of a chronic inflammatory lesion. Which of the following is NOT a typical microscopic finding in chronic inflammation?

Explanation

## Histological Features of Chronic Inflammation **Key Point:** Chronic inflammation is characterized by mononuclear cell infiltration (lymphocytes, macrophages, plasma cells) and tissue remodeling, NOT neutrophilic predominance. ### Microscopic Findings: Chronic vs. Acute Inflammation | Finding | Acute Inflammation | Chronic Inflammation | |---------|-------------------|----------------------| | **Predominant cell** | Neutrophils (PMNs) | Lymphocytes, macrophages, plasma cells | | **Microabscesses** | Common | Absent (unless secondary acute exacerbation) | | **Fibroblasts** | Minimal | Prominent; active collagen synthesis | | **Angiogenesis** | Minimal | Marked; new capillary formation | | **Duration** | Hours to days | Weeks to years | | **Tissue damage** | Exudative | Fibrotic, scarring | ### Why Option 0 is Incorrect **High-Yield:** Neutrophilic polymorphs (PMNs) and microabscesses are hallmark features of **acute inflammation**, not chronic inflammation. Their presence suggests an active acute phase or secondary acute exacerbation superimposed on chronic disease. **Clinical Pearl:** If you see neutrophils and microabscesses in a chronic lesion, think of acute-on-chronic inflammation (e.g., acute exacerbation of chronic osteomyelitis, or secondary bacterial infection of a chronic wound). ### Why the Other Options Are Correct 1. **Option 1** — Lymphocytes, macrophages, and plasma cells are the defining cellular infiltrate of chronic inflammation. 2. **Option 2** — Fibroblast proliferation and new collagen deposition are central to the reparative phase and tissue remodeling in chronic inflammation. 3. **Option 3** — Vascular proliferation (angiogenesis) is a hallmark of chronic inflammation, supporting the repair process and granulation tissue formation. **Mnemonic:** **MAC-FAN** = **M**acrophages, **A**ngiogenesis, **C**ollagen (fibroblasts), **F**ibroblasts, **A**ctive repair, **N**o neutrophils (in pure chronic form).