Medullary carcinoma of the thyroid gland. Clinical, pathological, and immunohistochemical features with review of the literature.

Twenty medullary carcinomas of the thyroid gland were examined for the presence of immunoreactive calcitonin, thyroglobulin, glucagon, keratin, gastrin/CCK, carcinoembryonic antibody (CEA), insulin, serotonin, adreno-corticotropic hormone (ACTH), prostatic acid phosphatase, and somatostatin using the immunoperoxidase peroxidase-antiperoxidase technique. In addition, they were stained with mucicarmine, alcian blue/periodic acid-Schiff (PAS), Grimelius, Congo red, crystal violet, and Fontana-Masson stains. Calcitonin-immunoreactive cells were absent in one tumor and present in 19 tumors (95%). Thyroglobulin was present in seven tumors (35%). Twenty tumors contained CEA-immunoreactive cells (100%). Fourteen cases were immunoreactive to serotonin (70%) and 12 were positive for somatostatin (60%). Glucagon- and gastrin/CCK-immunoreactive cells were found in two cases each (10%). Four tumors (20%) contained ACTH-immunoreactive cells and three cases (15%) were positive for prostatic acid phosphatase. Five cases (25%) contained keratin-immunoreactive cells. One case was immunoreactive to insulin (5%). Grimelius-positive cells were present in 19 of the cases (95%). Mucin-containing cells were present in 65% of the cases. The validity of the immunocytochemical localizations was tested by specific absorption of each antibody with the corresponding antigen. The demonstration of immunoreactivity for multiple antigens in each of the 20 cases suggests that the origin of medullary thyroid carcinomas is from a neuroendocrine cell potentially capable of producing numerous hormone substances. In addition, as the neoplastic cells in 35% of the tumors contained hormonal substances as well as thyroglobulin, it is suggested that papillary or follicular tumors mixed with a neuroendocrine component exist more commonly than previously suspected. Finally, psammoma bodies might be present in pure medullary carcinoma of the thyroid gland.