Medullary thyroid carcinoma is the third most common of the four types of thyroid cancer, less than papillary and follicular carcinoma, but more than undifferentiated carcinoma. Medullary thyroid carcinoma is derived from cells that are different from those of the thyroid gland, but are derived from parathyroid cells, called C cells. Strictly speaking, it is part of the cells of the thyroid gland, but it is relatively small. This part of the patient is mainly of a different origin because his treatment and the characteristics of his disease are completely different from ours. And there is a distinctive feature of medullary carcinoma, some of the patients have a significant family history. But most of them are also diagnosed through surgery. So it’s called medullary carcinoma because of its source of parathyroid C cells.