Which of the following pathological features is characteristic of lobar pneumonia but NOT typically seen in bronchopneumonia?

Explanation

## Pathological Distinction Between Lobar and Bronchopneumonia ### Lobar Pneumonia Characteristics **Key Point:** Lobar pneumonia is characterized by **consolidation of one or more complete lobes** with a **sharp demarcation** between affected and unaffected lung tissue. **High-Yield:** The consolidation typically follows anatomical lobar boundaries and progresses through four classic stages: 1. Congestion (edema, minimal exudate) 2. Red hepatization (fibrin, RBCs, neutrophils) 3. Gray hepatization (fibrin, neutrophils, RBC lysis) 4. Resolution (macrophage infiltration, resorption) ### Bronchopneumonia Characteristics **Key Point:** Bronchopneumonia shows **patchy, multifocal consolidation** that does NOT respect lobar boundaries. It is centered on **bronchi and bronchioles** rather than lobes. ### Comparative Table | Feature | Lobar Pneumonia | Bronchopneumonia | |---------|-----------------|------------------| | **Distribution** | One or more complete lobes | Patchy, multifocal, multiple lobes | | **Demarcation** | Sharp boundary | Indistinct, scattered | | **Primary site** | Alveoli (secondary to bronchitis) | Bronchi and bronchioles | | **Typical organism** | *Streptococcus pneumoniae* | *Staphylococcus aureus*, *Haemophilus*, viruses | | **Exudate type** | Fibrinopurulent | Mucopurulent | | **Stages** | Four classic stages | No distinct stages | **Clinical Pearl:** Lobar pneumonia is classically associated with *S. pneumoniae* in immunocompetent adults, whereas bronchopneumonia is more common in the very young, very old, immunocompromised, or post-aspiration settings. **Warning:** Do not confuse the **presence of neutrophils** or **bronchial involvement** as distinguishing features — both pneumonias contain neutrophilic exudate and may involve airways. The key distinction is **anatomical distribution** (lobar vs. patchy) and **demarcation** (sharp vs. indistinct).