Immunohistochemical features of paragangliomas

Immunohistochemistry is part of the routine diagnosis of the neuroendocrine tumors. In our study, we included 52 paragangliomas with various localizations by routine histology and immunohistochemistry. In order to increase the diagnostic specificity, a complex immunohistochemistry panel has been performed consisting of Bcl-2, Ki-67, Bax and Pituitary Adenylate Cyclase-Activating Peptide (PACAP), somatostatin, VIP and Calcitonin Gene Related Peptide (CGRP). After heat induced antigen retrieval, the immunostaining was performed by StreptABC using DAB as a chromogen. We were the first to demonstrate the presence of Bax and PACAP in paragangliomas. Some of the used markers are of prognostic value. The relationship between Bcl-2 and Bax is decisive in generating the final response to the input apoptotic signals. The Ki-67 antigen staining has gained wide acceptance in prognostic evaluation of other tumor types. We noted a small number of Ki-67 positive cases, which signifies a low mitotic activity of these tumors and a relatively high number of Bax positivities (32.9%) and the much lower number of Bcl-2 positivities (11.39%), and could explain the benign behaviour of paragangliomas.