Synaptophysin

This 38 kD transmembrane glycoprotein is located in presynaptic vesicles and is both chemically and topographically different from chromogranin. Other proteins in pre-synaptic vesicles include synaptobrevin, synaptotagmin, SNAP-25. SNAP receptor (SNARE), syntaxin and Rab3A4. In nerves, it is co-expressed with neurofilament whereas in solitary bronchial neuroendocrine cells, it is co-expressed with cytokeratins2. Antigenicity may be lost with prolonged fixation3.

Immunohistochemical expression

• presynaptic central and peripheral nervous system

• adrenal cortical cells, adrenal cortical adenomas and carcinomas4.

• adrenal medulla and phaeochromocytoma

• pancreatic islets

• neuroendocrine cells of:

  • the carotid body

  • skin

  • pituitary

  • thyroid

  • lung

  • pancreas

  • gastrointestinal tract

• see comparison of neuroendocrine markers

• paraganglioma

• pancreatic islet cell tumours

• medullary carcinoma of the thyroid

• all carcinoids, irrespective of their site of origin1

• pituitary adenoma

• parathyroid adenoma

• neuroblastoma, ganglioneuroblastoma, ganglioneuroma, central neurocytoma and ganglioglioma

Diagnostic utility

References

1Al-Khafaji et al. Immunohistologic analysis of gastrointestinal and pulmonary carcinoid tumours. Human Pathol 1998;29:992-9.

2Shy, S.W., Lee, W.H., Chou, M.C., Lai, Y.S. and Tu, Y.C. Small cell lung carcinoma: clinicopathological, immunohistochemical, and ultrastructural study. J Surg Oncol 1990;45:146-61.

3Hoog, A., V. E. Gould, et al. (1988). "Tissue fixation methods alter the immunohistochemical demonstrability of synaptophysin." Ultrastruct Pathol 12(6): 673-8.

4Erickson, L. A. and R. V. Lloyd (2004). "Practical markers used in the diagnosis of endocrine tumors." Adv Anat Pathol 11(4): 175-89.

©SMUHT/PW Bishop