Galanin immunoreactivity in paragangliomas but not in carcinoid tumors.

Galanin is a 29 to 30-amino acid neuropeptide involved in diverse regulatory effects in the central and peripheral nervous systems. Although galanin has been found in paragangliomas and other tumors, its expression has not been studied in carcinoid tumors arising in various locations. Galanin was detected in 62% (15/24) of adrenal pheochromocytomas, 40% (2/5) of jugulotympanic paragangliomas, and 18% (2/11) of carotid body paragangliomas, but was absent in 4 extra-adrenal pheochromocytomas and 3 metastatic or recurrent paragangliomas. All 26 carcinoid tumors were negative. Galanin may have limited utility as a diagnostic marker alone but would be most useful in conjunction with other immunohistochemical markers for the differential diagnosis of neuroendocrine tumors.