Chromogranins, including chromogranin A (CgA), are members of the granin family of neuroendocrine secretory proteins located in the secretory vesicles of neurons and endocrine cells.
In addition to the primary function chromogranins in granulogenesis of vesicle formation, CgA is the precursor for many functional peptides such as vasostatin, pancreastatin, catestatin, parastatin, serpenin, and other peptides that have many physiological functions (including autocrine, paracrine, and endocrine) in the corresponding neuroendocrine physiology.
Chromogranins are excellent indicatives of neuroendocrine differentiation.
Immunohistochemistry for Chromogranin was diffusely positive with punctate cytoplasmic positivity.
Immunohistochemically, the tumour cells were negative for PSA and positive for chromogranins (Fig.
In this case, immunostains for PSAS, prostate-specific acid phosphatase, cytokeratin 7, cytokeratin 20 were negative, while those for chromogranin and synaptophysin were strongly positive - these factors helped in the diagnosis.[sup.7]
Staining was positive for pan-cytokeratin and negative for chromogranins
, nonspecific esterase, synaptophysin, and S-100, supporting the diagnosis.
The World Health Organization's (WHO) definition of neuroendocrine tumours is 'morphofunctional' and is primarily based on microscopic characteristics, but incorporates immunohistological data (with such markers as the chromogranins
, synaptophysin and non-specific enolase), special stains (e.g.
A (CgA) is a common marker for these endocrine cells [21-23], and consequently it has been found that CgA is reduced in these patients .
A (CgA), a member of the granin family, is an acidic 439-amino acid protein with a widespread expression in endocrine cells and neurons (1-3).