## Diagnosis of Small Cell Lung Cancer: Role of Bronchoscopy ### Why Bronchoscopy with Endobronchial Biopsy is the Gold Standard **Key Point:** Bronchoscopy with endobronchial biopsy is the investigation of choice for central lung lesions suspicious for SCLC because it allows direct visualization, tissue sampling, and histopathological confirmation in a single procedure. **High-Yield:** SCLC typically arises from central airways (proximal bronchi), making it ideally accessible via bronchoscopy. The procedure can obtain adequate tissue for: - Histological diagnosis (small cell morphology) - Immunohistochemistry (CD56, synaptophysin, chromogranin A positivity) - Electron microscopy confirmation if needed ### Clinical Advantages | Feature | Bronchoscopy | CT-guided FNAC | Sputum Cytology | PET-CT | |---------|--------------|----------------|-----------------|--------| | **Tissue yield** | High (>90%) | Moderate (70–80%) | Low (30–40%) | None (imaging only) | | **Direct visualization** | Yes | No | No | No | | **Histology available** | Yes | Yes (limited) | Yes (limited) | No | | **Central lesions** | Optimal | Suboptimal | Variable | N/A | | **Procedural risk** | Low | Very low | None | None | **Clinical Pearl:** Central hilar masses in smokers with SCLC presentation warrant bronchoscopy first because the lesion is often endobronchial and easily accessible, avoiding unnecessary invasive procedures. ### Role of Other Investigations - **Sputum cytology:** Low sensitivity (30–40%) for SCLC; useful as screening but not diagnostic. - **CT-guided FNAC:** Better for peripheral lesions; less ideal for central masses where bronchoscopy is safer and more direct. - **PET-CT:** Staging tool, not diagnostic; used AFTER histological confirmation to assess metastases and guide treatment planning. **Mnemonic:** **BRONC** = Best for central, Readily accessible, Obtains tissue, No delay, Confirms diagnosis [cite:Robbins 10e Ch 15] 
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