ABSTRACT

There are two main groups of thyroid carcinomas, (1) carcinomas arising from thyroid follicular cells, the thyroid cells “proper,” and (2) carcinomas arising from the neuroendocrine C-cells (calcitonin producing cells). The difference between the main groups is of major biological importance and has consequences for diagnosis and follow-up, as described in this chapter. In the thyroid, like in other organs, cells from connective tissue, lymphoid cells, etc. may also give rise to malignant tumors (e.g., sarcomas, lymphomas), but those tumors are not described here.