IMMUNOHISTOCHEMICAL AND ULTRASTRUCTURAL ANALYSIS OF MEDULLARY CARCINOMA OF THYROID IN RELATION TO HORMONE PRODUCTION

Abstract

Eighteen cases of medullary carcinoma of the thyroid were analyzed immunohistochemically for calcitonin- and ACTH-containing cells, and tumor cells in 8 cases were examined by EM and analyzed by manual and computer procedures with particular attention paid to the size and quality of secretory granules. Calcitonin- and ACTH-containing cells were found singly or in clusters in 14 and 11 tumors, respectively. In 4 cases, calcitonin-positive cell clusters and an increase in number of singly scattered C cells were seen apart from the main tumor, suggesting a multicentric nature of certain medullary carcinomas. Some ACTH-containing cells were apparently also positive for calcitonin. In a case of familial Sipple disease, follicular lining cells were replaced in areas with ACTH-containing cells. Three to 5 frequency distribution curves of the size of secretory granules were obtained in all of 6 cases analyzed, and at least 2 types of granule matrix were identified.