All of the following are characteristic features of lobar pneumonia EXCEPT:

Explanation

## Distinguishing Lobar vs Bronchopneumonia **Key Point:** Lobar pneumonia and bronchopneumonia differ fundamentally in anatomical distribution, causative organisms, and pathological progression. Understanding these distinctions is essential for NEET PG pathology. ### Lobar Pneumonia: Defining Features | Feature | Lobar Pneumonia | |---------|------------------| | **Distribution** | Entire lobes; segmental consolidation | | **Bronchial involvement** | Bronchi are PATENT; minimal airway involvement | | **Common organism** | *Streptococcus pneumoniae* (most frequent) | | **Pathological stages** | Red → Gray → Resolution (classic 4 stages) | | **Exudate type** | Fibrinous; rich in fibrin and inflammatory cells | | **Pleural involvement** | Fibrinous pleuritis common | | **Onset** | Sudden; preceded by chill and fever | ### Bronchopneumonia: Contrasting Features | Feature | Bronchopneumonia | |---------|-------------------| | **Distribution** | Patchy; around bronchi and bronchioles | | **Bronchial involvement** | Bronchi are OCCLUDED by purulent exudate | | **Common organisms** | *Staphylococcus aureus*, *Haemophilus influenzae*, gram-negatives | | **Pathological stages** | No classic stages; suppuration and abscess formation | | **Exudate type** | Purulent; neutrophil-rich | | **Pleural involvement** | Less common | | **Onset** | Insidious; often secondary to aspiration or viral infection | **High-Yield:** The key distinction is **bronchial patency**. In lobar pneumonia, bronchi remain open (patent), allowing air to enter consolidated tissue. In bronchopneumonia, bronchi are plugged with purulent material, causing patchy infiltrates around airways. ### Why Option 4 is Incorrect Option 4 states: "Bronchi remain patent with minimal involvement, leading to patchy infiltrates." This is a **contradictory and incorrect statement** for lobar pneumonia: - **Patent bronchi** ✓ (correct for lobar pneumonia) - **Patchy infiltrates** ✗ (this is the hallmark of *bronchopneumonia*, not lobar pneumonia) Lobar pneumonia produces **consolidation of entire lobes**, not patchy infiltrates. Patchy infiltrates around bronchi are the defining feature of bronchopneumonia. **Clinical Pearl:** On chest X-ray, lobar pneumonia shows a dense, homogeneous consolidation that respects lobar boundaries ("air bronchogram" may be visible). Bronchopneumonia shows scattered, ill-defined opacities around the hilum and bases. **Mnemonic:** **LOBAR = LOBULAR + AIRWAY PATENT** - **L**obar = **L**arge consolidated **L**obe - **B**roncho = **B**ronchi **B**locked (occluded) [cite:Robbins 10e Ch 15]