[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Endocrine system](https://durgical.com/en/general-pathology/areas/endocrine/) › Medullary thyroid carcinoma # Medullary thyroid carcinoma - Lesion A thyroid cancer of the calcitonin-making cells. Some families inherit it through the RET gene, so relatives are tested and operated on early. Updated Nov 12, 2026 ## Key points - C-cell origin: calcitonin is the tumour marker; CEA also rises. - Amyloid stroma from calcitonin precursors: Congo red positive, apple-green birefringence. - Sporadic tumours are solitary; familial ones are bilateral, multicentric, with C-cell hyperplasia in the surrounding gland. - RET gain of function: germline in MEN2A, MEN2B and familial medullary carcinoma; somatic in many sporadic cases. - Prophylactic thyroidectomy in RET carriers, timed by the specific mutation. - Can secrete other peptides (VIP, serotonin, ACTH): diarrhoea, carcinoid-like flushing, Cushing syndrome. ## What it is Medullary carcinoma is a neuroendocrine tumour of the parafollicular C cells, which derive from neural crest via the ultimobranchial body. It secretes calcitonin, and its stroma contains amyloid made of calcitonin. Most cases are sporadic, but a substantial minority are familial in MEN2A, MEN2B or familial medullary carcinoma, all caused by germline RET activating mutations. ## Structure - Gross: firm grey-tan, sometimes gritty nodule, often in the upper half of the lobes where C cells live. - Micro: polygonal to spindle cells in nests, trabeculae or sheets; salt-and-pepper chromatin. - Acellular amyloid in the stroma. - Electron microscopy: membrane-bound neurosecretory granules. - Familial: multifocal C-cell hyperplasia, the precursor lesion. ## Markers - Calcitonin - CEA - Chromogranin - Synaptophysin - TTF1 - Congo red ## Clinical notes - Neck mass or nodal metastasis; diarrhoea from calcitonin or VIP. - Serum calcitonin and CEA follow disease after surgery. - Every patient with medullary carcinoma is offered germline RET testing. ## Memory aid Medullary is the thyroid's neural crest cousin: it makes calcitonin, folds it into amyloid, and the RET gene tells you whether the family is at risk. ## Test yourself Think of the answer, then tap the question to see it. ## What is the amyloid in medullary thyroid carcinoma made of? Calcitonin (procalcitonin) polypeptides secreted by the tumour cells. ## Which precursor lesion is seen in familial medullary carcinoma? Multicentric C-cell hyperplasia. ## Why are RET mutation carriers offered thyroidectomy? Nearly all will develop medullary carcinoma, which is curable only if removed before it spreads. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/general-pathology/medullary-thyroid-carcinoma/) [More Pathology questions →](https://durgical.com/en/practice/?f=pathology) ## Elsewhere in DurgiPedia - [Thyroid follicles, C cells and parathyroid](https://durgical.com/en/histology/thyroid-follicles-c-cells-and-parathyroid/) - [Pharyngeal pouches: tonsil, thymus, parathyroids and C cells](https://durgical.com/en/embryology/pharyngeal-pouches-tonsil-thymus-parathyroids-and-c-cells/) - [Special stains in diagnosis: Congo red, Prussian blue, PAS, Ziehl–Neelsen, Gram](https://durgical.com/en/general-pathology/special-stains-in-diagnosis-congo-red-prussian-blue-pas-ziehl-neelsen-gram/) - [Tumour markers: serum and tissue, and what each one is for](https://durgical.com/en/general-pathology/tumour-markers-serum-and-tissue-and-what-each-one-is-for/) ## Connections ## Related 5 - [Multiple endocrine neoplasia (MEN) syndromes](https://durgical.com/en/general-pathology/multiple-endocrine-neoplasia-syndromes/) - [Thyroid cancer: genetics and radiation](https://durgical.com/en/general-pathology/thyroid-cancer-genetics-and-radiation/) - [Pheochromocytoma and paraganglioma](https://durgical.com/en/general-pathology/pheochromocytoma-and-paraganglioma/) - [Restrictive cardiomyopathy and cardiac amyloidosis](https://durgical.com/en/general-pathology/restrictive-cardiomyopathy-and-cardiac-amyloidosis/) - [Tumour markers: serum and tissue, and what each one is for](https://durgical.com/en/general-pathology/tumour-markers-serum-and-tissue-and-what-each-one-is-for/) ## Related conditions 4 - [Medullary thyroid carcinoma](https://durgical.com/en/conditions/medullary-thyroid-carcinoma/) - [Multiple endocrine neoplasia (MEN 1, 2A, 2B)](https://durgical.com/en/conditions/multiple-endocrine-neoplasia/) - [Amyloidosis](https://durgical.com/en/conditions/amyloidosis/) - [Phaeochromocytoma](https://durgical.com/en/conditions/phaeochromocytoma/) [← All of general pathology](https://durgical.com/en/general-pathology/) Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given. Sources: [Thyroid Cancer Treatment (PDQ®)–Health Professional Version](https://www.cancer.gov/types/thyroid/hp/thyroid-treatment-pdq) (National Cancer Institute, 2025); [Multiple endocrine neoplasia: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/multiple-endocrine-neoplasia/) (MedlinePlus, US National Library of Medicine, 2025). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/general-pathology/medullary-thyroid-carcinoma/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/medullary-thyroid-carcinoma/