Immunohistochemical hormone content in medullary and undifferentiated thyroid carcinoma and prognosis after surgery.

Immunohistochemical determinations in tissue specimens of medullary and "undifferentiated" thyroid carcinomas were carried out with antisera against calcitonin, calcitonin-gene related peptide (CGRP), somatostatin, and also thyroglobulin, using the PAP method. All 8 samples of medullary carcinoma stained positive with antisera against calcitonin and CGRP, 7 samples were also positive for somatostatin. Out of 22 cases initially diagnosed as "undifferentiated thyroid carcinoma" 3 revealed positivity for calcitonin, 2 for CGRP, and 1 for somatostatin. Congo red stain for amyloid, performed several years ago in 2 of these 3 cases, had been negative. The patients with medullary carcinoma survived longer than those with "undifferentiated" carcinoma. One patient of the latter group, but with calcitonin, CGRP, and somatostatin immunoreactivity in the tumour tissue, is now alive and well, more than 4 a after initial treatment.