Immunohistochemistry markers for the diagnosis of neuroendocrine tumors are part of the diagnosis of PGL, and the markers included in the immunohistochemistry panel are Bcl-2, Ki-67, Bax, and pituitary adenylate cyclase activating peptide (PACAP), somatostatin, vasoactive intestinal peptide (VIP), and calcitonin gene-related peptide (CGRP), to increase diagnostic specificity. Here, VIP is linked to neuroendocrine neoplasm.