Also found in: Acronyms, Encyclopedia, Wikipedia.

medullary carcinoma of thyroid

A neuroendocrine tumour that comprises ±5% of thyroid cancers, arising in the C (parafollicular) cells of the ultimobranchial cleft—i.e., neural crest origin. It is either sporadic (70–90% of cases) or inherited (10–30%) as part of the autosomal dominant multiple endocrine neoplasia (MEN) types 2A or 2B, the latter in association with mutations of the RET proto-oncogene. The average age at diagnosis is 50; it is slightly more common in women.

Clinical findings
Related to local growth and compromised of regional structures; increased calcitonin causes hypercalcaemia, hypertension, paraneoplastic syndromes (e.g., Cushing syndrome) and neuromas.

Clinical forms
• Sporadic—70–90% of cases, mean age of onset 45; presenting as a solitary “cold nodule” (by thyroid scan), which may be accompanied by intractable diarrhoea and Cushing’s syndrome. 
• Familial—10–30% of cases, mean age of onset 35; multifocal and bilateral, accompanied by C-cell hyperplasia of residual thyroid tissue; familial MCT is often autosomal dominant and associated with multiple endocrine adenomatosis, usually type II (which has a germline abnormality on chromosome 10, an earlier age of onset and is often bilateral) or occasionally type III (IIb; less common, but more aggressive and rarely a non-aggressive form of MCT that is not associated with other neural or endocrine lesion).

MCTs may produce ACTH-like substance, biogenic amines, CEA, corticotropin-releasing factor, NGF, prolactin-releasing hormone, prostaglandins, melanin-stimulating hormone, histaminase, beta-endorphin, 5-hydroxytryptamine, serotonin, somatostatin, thyroglobulin.

Thyroid function tests
Usually normal.

Risk factors
Family history of multiple endocrine neoplasia MEN 2A or 2B, history of phaeochromocytoma, mucosal neuromas, hyperparathyroidism; RT to head or neck, the risk of radiation-induced thyroid nodularity and carcinoma increases with radiation dose and decreases the older the person was at the time of irradiation.
Metastases to
Cervical lymph nodes, mediastinum, lungs, liver, bone, brain, adrenal glands.

Total thyroidectomy, radioiodine.
70–80% 5-year survival; sporadic MCT has a 50% 10-year survival; 10- and 20-year survival is 63% and 44% respectively (papillary thyroid carcinoma has 95% 10-year survival). 70% develop nodal metastasis.

Medullary thyroid cancer (MTC)

A slow-growing tumor associated with MEN.
References in periodicals archive ?
On Wednesday MTC MD Miguel Geraldes told the Economist that the mobile payment solution service, called MTC Money will be used mainly as a tool to reward loyal customers by offering an array of convenient mobile payment services.
gov, mail them to MTC Public Information, 101 Eighth Street, Oakland, CA 94607-4700, or fax to 510.
Taxpayers who have long-term unused MTC are entitled to an MTC equal to the greater of the AMT refundable credit amount or the amount of allowable MTC under the preexisting Sec.
The brains of the MTC is a nonproprietary, full function PID controller that comes with a five-year warranty.
This type of functionality adds real value, both for the MTC staff, and to the many customers we interact with daily.
FeRx is committed to expanding the applications of its MTC drug delivery platform and we believe that gene therapy marks an exciting opportunity for expansion of our product pipeline in oncology," said Jacqueline Johnson, Ph.
Tenants enjoy the crucial benefit of extremely reliable operation, since each MTC site has a central office switch, utilize dual fiber entry, and features "Sonet" (Synchronous Optical Network) or redundant network architecture.
Mines said another support for the MTC position is the number of system operators--the people who manage the electronic bulletin boards--who work all over the United States.
Avocent's technology enables the MTC staff and enterprise customers to remotely access, monitor and control any device within the MTC environment, demonstrating how the technology will perform in a local or remote environment.
In manufacturing, MTC Transformers conserves natural resources by reusing materials and by customizing transformers for wind, solar, and hydro projects.
Bruce Johnson, Chair of the MTC Executive Committee and Utah State Tax Commissioner, presided.