Chromogranin A

Chromogranin A (CgA) is an acidic secretory glycoprotein found in the secretory granules of neuroendocrine cells and neurons, as is a member of the granin family of proteins. It can be used both for immunohistochemical stains and as a serum marker ⁴. 

Immunohistochemistry

Chromogranin A is useful in identifying tissues of neuroendocrine origin, especially neuroendocrine tumors, as well as dysplastic neurons (e.g. in ganglioglioma) ⁵. 

Serum biomarker

Chromogranin A can be used to aid detection and surveillance of neuroendocrine tumors.  It can be elevated with:

• pheochromocytoma
• medullary thyroid carcinoma
• enterochromaffin and pancreatic islet cell tumors
• autoimmune chronic atrophic gastritis
• gastrinoma
• multiple endocrine neoplasia syndrome type 1
• carcinoid tumors: especially malignant gastric carcinoid tumors

Serum CgA values can also be used to trend neuroendocrine tumor burden, but caution should be exercised if the patient is being treated with somatostatin analogs, as they may depress CgA levels.

See other tumor markers here.