Chromogranin A

Specificity: A 48-75 kDa acid calcium-binding glycoprotein.

Staining characteristics: Granular cytoplasmic.

Function: One of a family of acid calcium-binding glycoproteins closely associated with neurosecretory granules in virtually all neurons and neuroendocrine cells. Diagnostically, chromogranin A is the most important of that glycoprotein family. Probably the major target of the argyrophilic Grimelius staining reaction. Post-translational processing creates biologically active fragments with autocrine and paracrine functions.

Normal cell distribution: Virtually all neurons and neuroendocrine cells.

Chromogranin A+: Most neural and epithelial neuroendocrine tumors.

• Pituitary adenoma
• Parathyroid tumors
• Pancreatic islet cell tumors
• Medullary thyroid carcinoma
• Carcinoid tumors of the foregut (NOT hindgut)
• Small cell carcinoma
• Merkel cell carcinoma
• Some multiphenotypic tumors such as malignant rhabdoid and desmoplastic small round cell
• Ganglioneuroblastoma
• Ganglioneuroma
• Ganglioglioma
• Phaeochromocytoma
• Sympathetic Paraganglioma and some parasympathetic
• Some oligodendrogliomas

Chromograning A-:

• Carcinoid tumors of the hindgut (NOT foregut)
• Most glial tumors
• Meningioma
• Choroid plexus tumours
• Schwannoma
• Malignant melanoma
• Adrenocortical tumours
• Other carcinomas
• Mesothelioma
• Sarcomas

((()))