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.

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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.