IMMUNOHISTOCHEMISTRY, CHROMOGRANIN A

What this test checks

Detects chromogranin A, a protein stored in secretory granules of neuroendocrine cells. A key marker for confirming neuroendocrine tumours (NETs) — carcinoid tumours, pancreatic NETs, and small cell carcinomas.

Why do people get this test?

Neuroendocrine tumours are a distinct cancer type with specific treatments (somatostatin analogues, targeted therapies). Chromogranin A confirms the diagnosis and guides management.

When you should consider this test

• When a tumour is suspected to be a neuroendocrine tumour (carcinoid, pNET)
• When classifying small cell lung cancer
• As part of a neuroendocrine tumour panel (with synaptophysin)

How to prepare

No preparation needed — performed on biopsy or surgical tissue.