SYP is a calcium binding integral-membrane glycoprotein, 38 kDa of presynaptic vesicles in all neurons and corresponding vesicles in all neuroendocrine (NE) cells. Moreover SYP is detected in choroid plexus epithelium. Staining is also seen in adrenal cortical cells, goblet cells and Paneth cells, probably due to a closely related protein.
SYP is detected in virtually all neuronal tumours: Neuroblastoma, ganglioneuroblastoma, ganglioneuroma, ganglioglioma, central neurocytoma, and phaeochromocytoma/paraganglioma. SYP may also be detected in other neural crest derived tumours like oligodendroglioma, astrocytoma and ependymoma, however, to a varying extend. Moreover synaptophysin is detected in NE tumours like pancreatic islet tumours, carcinoid and neuroendocrine carcinoma, small cell carcinoma, medullary thyroid carcinoma, and pituitary and parathyroid adenomas. Also adrenal cortical tumours stain for synaptophysin.
SYP is a sensitive marker for the identification of neuronal and NE tumours and NE differentiation. However, it is not as specific as chromogranin A. SYP may also be used for the identification of adrenal cortical tumour.
It is difficult to identify a reliable and robust positive tissue control for SYP. At present the best recommendation is still to use colon or appendix as control and to calibrate the protocol to give an intense staining reaction of the axons of the Auerbach’s and Meissner’s plexus with a high-level expression of SYP. The endocrine cells of the mucosa must show an at least moderate staining reaction and importantly the majority of goblet cells in the mucosa must show an at least weak to moderate cytoplasmic staining Nordic Immunohistochemical Quality Control, SYP run 43 2015 Page 5 of 7 reaction. The reason for the staining reaction of goblet cells in the colon mucosa is still not known. However, as all Abs could give this staining pattern and these cells only show a weak to moderate staining reaction, the capability to obtain a positive SYP reaction in the goblet cells is thus superior to nerves as critical staining quality indicator for SYP. No staining must be seen in the vast majority of smooth muscle cells.
Selected references
Erickson LA, Lloyd RV. Practical markers used in the diagnosis of endocrine tumors. Adv Anat Pathol. 2004 Jul;11(4):175-89. Morrison CD, Prayson RA. Immunohistochemistry in the diagnosis of neoplasms of the central nervous system. Semin Diagn Pathol. 2000 Aug;17(3):204-15. Portela-Gomes GM, Hacker GW, Weitgasser R. Neuroendocrine cell markers for pancreatic islets and tumors. Appl Immunohistochem Mol Morphol. 2004 Sep;12(3):183-92. Wick MR. Immunohistology of neuroendocrine and neuroectodermal tumors. Semin Diagn Pathol. 2000 Aug;17(3):194-203.
22.04.15 - MV/LE