Immunohistochemical characterization of parafollicular cell adenoma, medullary carcinoma and follicular adenocarcinoma in thyroid of horses

Abstract

An Immunohistochemical examination was conducted using commercially available primary antibodies to evaluate their utility for differential diagnosis of equine thyroid tumors i.e. non-functional C-cell adenoma, medullary carcinoma and follicular adenocarcinoma. The primary antibodies used in the study were antibodies against calcitonin, calcitonin-gene-related peptide (CGRP), thyroglobulin, chromogranin A, neuron specific enolase (NSE), synaptophysin and somatostatin. Calcitonin, NSE and synaptophysin were found to be useful to identify the origin of tumors as C-cells and thyroglobulin as follicular epithelial cells. In addition, it was found that detection of CGRP and chromogranin A is related with the functional status of C-cells. The carcino-related-gene (CRG) product, bcl-2, was positive in medullary carcinoma and follicular adenocarcinoma, and weakly positive to negative in non-functional C-cell adenoma. Another CRG product, p53, was positive in non-functional C-cell adenoma and follicular adenocarcinoma, and negative in medullary carcinoma. These results suggest that the expression pattern of 9 antigens used may be of help for the differential diagnosis of these tumors.