Small cell lung cancer (SCLC) is characterized by which of the following neuroendocrine markers?

Question

Accepted Answer

C. Chromogranin A and synaptophysin. ## Neuroendocrine Differentiation in SCLC

**Key Point:** Small cell lung cancer is a high-grade neuroendocrine malignancy that consistently expresses neuroendocrine markers.

### Diagnostic Markers

| Marker | SCLC | Non-SCLC | Adenocarcinoma |
|--------|------|----------|----------------|
| Chromogranin A | ✓ (>90%) | ✗ | ✗ |
| Synaptophysin | ✓ (>90%) | ✗ | ✗ |
| CD56 | ✓ (>90%) | ✗ | ✗ |
| CEA | ✗ | ✓ | ✓ |
| TTF-1 | ✓ (>90%) | ✓ | ✓ |

**High-Yield:** Chromogranin A and synaptophysin are the **gold standard neuroendocrine markers** for SCLC diagnosis. These are detected by immunohistochemistry on biopsy or cytology specimens.

### Clinical Significance

- **Chromogranin A** is also elevated in serum and can be used as a tumor marker for monitoring treatment response and recurrence.
- **Synaptophysin** is highly specific for neuroendocrine differentiation.
- Both markers help distinguish SCLC from non-small cell lung cancer (NSCLC), which typically lacks these markers.

**Clinical Pearl:** SCLC also frequently co-expresses TTF-1 (thyroid transcription factor-1), which is a pan-lung cancer marker but is not specific for neuroendocrine differentiation.

**Mnemonic:** **SCLC = SYN-CHRO** — **SYN**aptophysin and **CHRO**mogranin A are the hallmark markers.

![Lung Cancer — Small Cell diagram](https://mmcphlazjonnzmdysowq.supabase.co/storage/v1/object/public/blog-images/explanation/3510.webp)

Answer

A. PSA and PAP

Answer

B. HCG and AFP

Answer

D. CEA and CA 19-9

Small cell lung cancer (SCLC) is characterized by which of the following neuroendocrine markers?

Explanation

Neuroendocrine Differentiation in SCLC

Diagnostic Markers

Clinical Significance

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Marker	SCLC	Non-SCLC	Adenocarcinoma
Chromogranin A	✓ (>90%)	✗	✗
Synaptophysin	✓ (>90%)	✗	✗
CD56	✓ (>90%)	✗	✗
CEA	✗	✓	✓
TTF-1	✓ (>90%)	✓	✓