Medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) constitutes 5–10% of all thyroid carcinomas and is the third most common type of thyroid cancer following papillary and follicular carcinomas.

It is derived from the parafollicular C cells and in this regard differs from the follicular cell-derived papillary and follicular carcinomas both clinically and pathologically.

MTC exhibits a more aggressive clinical behaviour and is more difficult to treat.

This is in contrast to papillary and follicular carcinomas, which respond to radioactive iodine and therefore may have a favourable clinical course, even in case of recurrence or metastasis.

MTC 1 cm in size is typically referred to as ‘micro-MTC’. Regional lymph nodes are the most common sites of metastasis for MTC. They are involved in 50% of cases at the time of presentation.

When distant metastasis occurs, the most frequently involved organs are liver, lung, bone and mediastinum.

Medullary thyroid carcinoma intracranial metastases

Hypercortisolism may also be due to ectopic secretion of ACTH usually by tumors, most commonly small-cell carcinoma of the lung, thymoma, carcinoid tumors, pheochromocytomas, and medullary thyroid carcinoma.