Background/objective: Medullary thyroid carcinoma may mimic wide variants of benign and malignant thyroid neoplasm. This study is designed to analyze the role of immunohistochemical markers [calcitonin, carcinoembryonic antigen (CEA), and vimentin] in the diagnosis of medullary thyroid carcinoma and to determine their prognostic value.
Material and methods: An immunohistochemical study using a panel of monoclonal antibodies for calcitonin, CEA, and vimentin was carried out on paraffin sections of 24 cases of sporadic medullary thyroid carcinoma of different stages collected from the pathology departments of Zagazig University and Cairo University.
Results: All neoplastic cells showed immunoreactivity for calcitonin, CEA, and vimentin. Strong reactivity (++++) for calcitonin was observed in all cases without lymph node metastasis (10/10; 100%), whereas its weak reaction (+ or ++) was associated with cases of advanced stages (9/14; 64%). However, strong CEA positivity was highly associated with cases of advanced stages (9/14; 64%). For vimentin, all cases showed vimentin expression with different grades of intensity and this was correlated with the stage of medullary thyroid carcinoma, but not with other clinicopathologic variables.
Conclusion: The positivity of all cases for calcitonin and CEA supports the diagnosis of medullary thyroid carcinoma. Weak immunoreactivity for calcitonin and strong CEA immunoreactivity are associated with a poor prognosis. Vimentin expression indicates epithelial mesenchymal transition phenomena with invasiveness and metastatic potential.