This study demonstrates a surprisingly high prevalence of sporadic forms of medullary thyroid carcinoma in patients with nodular thyroid disease. Such forms of medullary thyroid carcinoma seem to be unrelated to iodine intake and may be pure or mixed with a follicular carcinoma. In these mixed thyroid carcinomas, only the neoplastic follicular pattern was seen on both cytological and histological examination. Routine measurements of serum calcitonin levels should therefore be considered an integral part of the diagnostic evaluation of thyroid nodules. Indeed, increasing the accuracy of diagnosis of medullary thyroid carcinoma encourages the surgeon to perform more radical treatment, thus achieving more frequent normalization of post-operative serum calcitonin levels.

Cutaneous metastases from thyroid neoplasia are very rare. Most patients presenting with such a disease have also both internal metastases and a very enlarged thyroid gland. We reported here 2 patients presenting with differentiated thyroid microcarcinoma which was revealed by a solitary scalp lesion. The positive immunoperoxidase staining for thyroglobulin (TG) in the skin tumour cells asserted the diagnosis of metastatic thyroid carcinoma. The thyroid neoplastic micronodular formation was unrecognized by ultrasonography and it was only found at serial histological examination of the thyroid gland entirely removed during surgery. Histological procedure showed a solitary follicular microcarcinoma (diameter = 0.5 cm) in 1 patient, and two differentiated microcarcinoma, a follicular microcarcinoma (diameter = 0.4 cm) in a lobe and a follicular-papillary carcinoma (diameter = 0.5 cm) in the other lobe, in the second patient.

Our report is the first immunocytochemical study of the principal elements of the basement membrane (BM) and connective tissue in normal and adenomatous human anterior pituitaries. In normal tissues, both the parenchymatous BM limiting the endocrine cell cords and the endothelial BM around the capillaries were continuous and were stained with anti-laminin (LM), anti-type IV collagen (CIV) and anti-fibronectin (FN) antisera. Antiserum to type I collagen (CI) stained the connective tissue only. The same antigens were investigated in 23 human pituitary adenomas, 6 of them having been diagnosed as locally invasive by the radiologist and the neurosurgeon. In all cases a lack of cordal structure was observed and the parenchymatous BM was completely absent (9 cases) or fragmented (14 cases). No correlation could be established between the extent of parenchymatous BM alterations and the invasive behaviour of the tumour. In contrast, a continuous endothelial BM was observed around the blood vessels in all cases and its presence was confirmed in double immunofluorescence experiments using anti-von Willebrand factor and anti-LM or anti-CIV antisera. Anti-FN and CI also stained the wall of the vessels. The tumours showed arterial development, in addition to the capillaries found in normal tissue. The present results favour the hypothesis of a decreased synthesis of parenchymatous BM by human adenomatous pituitary cells in comparison with normal cells and show that these tumours are the site of an active arterial neovascularization.

Calcitonin (CT) is the most sensitive tumor marker for medullary thyroid carcinoma available, but it lacks specificity. Chronic renal failure (CRF) is known to be associated with elevations of serum immunoreactive calcitonin. Using an immunoradiometric assay to detect only mature CT, we evaluated the basal CT level and its response to pentagastrin in 30 patients with CRF and compared these data with those obtained in 71 controls. Basal mature CT was significantly higher (p < 0.05) in patients with CRF (3.55 pg/mL) than in controls (2.00). Among these patients, 20% had basal CT levels more than 10 pg/mL with a maximum of 51 pg/mL. Peak CT values (highest value obtained 3 or 5 minutes after pentagastrin) were comparable in the two groups. Among patients with CRF, 10% had peak CT values greater than 30 pg/mL with a maximum of 53 pg/mL. In this group of patients, no correlation was found between CT (at any time during the test) and parathyroid hormone, calcium, phosphate, or creatinine clearance. Men had significantly higher CT values compared with women at each time point tested, including peak values. Patients with CRF, who have not yet undergone dialysis, have moderately elevated basal CT levels, but have normal pentagastrin-stimulated peak CT levels.

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