[Classification and epidemiology of thyroid tumors].

Thyroid diseases are the most prevalent endocrine diseases. Faced with a thyroid enlargement or nodule, it is a challenge for the physician to determine with the best sensibility and specificity and the least cost which one are benign tumours and which are malignant neoplasms that need to be removed. The prevalence of solitary nodules is 1 to 5%. Only 2 to 12% of these nodules are cancers. Papillary and follicular carcinomas, two carcinomas derived from follicular cells, are the most common types and occur more frequently in women. Both have a good prognosis. Medullary carcinoma derives from C-cells. Familial forms have to be searched. Anaplastic carcinoma and other malignant tumours are less frequent but have poor prognosis.