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

Evaluation of somatostatin as a plasma tumor marker in medullary thyroid carcinoma

Somatostatin (SRIF) immunoreactivity has been frequently reported in tumor tissues of cell types, belonging to the APUD system, including medullary thyroid carcinoma (MTC). However, the value of SRIF as a plasma tumor marker for MTC is controversial. We have measured SRIF plasma levels in 35 patients with different stages of MTC to evaluate the use of SRIF as a plasma tumor marker compared to the current "gold standard" calcitonin (CT). The median SRIF value in healthy controls was 36.5 pg/mL, the upper limit of normal was defined at the controls. The median value was 28 pg/mL (p = 0.37, Mann-Whitney U test). Five patients in the control group and three in the MTC group had SRIF levels that exceed the 95th percentile. SRIF and CT levels correlated only weakly (0.38), as determined by the Spearman rank order correlation test. Pentagastrin stimulation led to a diagnostic increase in SRIF levels in only one of five MTC patients. During selective venous catheterization, diagnostic gradients for CT, allowing tumor localization, could be demonstrated, whereas measurement of SRIF levels did not aid in tumor detection. Although SRIF immunostaining may be valuable as an additional marker in the histochemical diagnosis of MTC, SRIF has no value as a plasma tumor marker in the diagnosis of this disease.

Medullary carcinoma of the thyroid with metastasis to the pituitary gland

A case of metastatic medullary thyroid carcinoma presenting with anterior pituitary dysfunction is reported. Initial evaluation revealed an intrasellar mass at a time when serum calcitonin and carcinoembryonic antigen levels were elevated, and histological analysis of resected tissue demonstrated the presence of metastatic medullary carcinoma of the thyroid. Immunohis-tochemical analysis confirmed the presence of calcitonin in the tumor cells. Like other malignant processes, metastatic medullary carcinoma of the thyroid may involve the pituitary gland and should be included in the differential diagnosis in the appropriate clinical setting.

Immunocytochemical localization and identification of prosomatostatin gene products in medullary carcinoma of human thyroid gland

Thirty-three cases of histologically proven calcitonin-positive medullary thyroid carcinoma were studied immunocytochemically for the occurrence of prosomatostatin-related peptides. Positive cells, identified with a panel of antisera raised against four different regions of the prosomatostatin molecule, were found in 100% of the tumors. Most but not all somatostatin-positive cells were also immunoreactive for calcitonin. Notably, seven patients harboring somatostatin-rich tumors revealed a more favorable clinical course. The results (1) indicate that somatostatin production is a universal concomitant of thyroid medullary carcinoma, (2) suggest that these cells are likely to produce a somatostatin precursor molecule similar to mammalian prosomatostatin, and (3) imply that somatostatin-reactive cells may have as yet unknown roles in these tumors, possibly in the realm of paracrine and autocrine regulation of cell growth.