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Medullary thyroid cancer (MTC) is a form of thyroid carcinoma which originates from the parafollicular cells (C cells), which produce the hormone calcitonin.〔Hu MI, Vassilopoulou-Sellin R, Lustig R, Lamont JP. ("Thyroid and Parathyroid Cancers" ) in Pazdur R, Wagman LD, Camphausen KA, Hoskins WJ (Eds) (Cancer Management: A Multidisciplinary Approach ). 11 ed. 2008.〕 Medullary tumors are the third most common of all thyroid cancers. They make up about 3% of all thyroid cancer cases. Approximately 25% of medullary thyroid cancer is genetic in nature, caused by a mutation in the RET proto-oncogene. This form is classified as familial MTC. When MTC occurs by itself it is termed sporadic MTC. When it coexists with tumors of the parathyroid gland and medullary component of the adrenal glands (pheochromocytoma) it is called multiple endocrine neoplasia type 2 (MEN2). It was first characterized in 1959. ==Signs and symptoms== The major clinical symptom of metastatic medullary thyroid carcinoma is diarrhea; occasionally a patient will have flushing episodes. Both occur particularly with liver metastasis, and either symptom may be the first manifestation of the disease. The flushing that occurs in medullary thyroid carcinoma is indistinguishable from that associated with carcinoid syndrome. In MTC, the flushing, diarrhea, and itching (pruritis) are all caused by elevated levels of calcitonin gene products (calcitonin or calcitonin gene-related peptide).〔 Alternatively, the flushing and diarrhea observed in carcinoid syndrome is caused by elevated levels of circulating serotonin. Medullary thyroid carcinoma may also produce a thyroid nodule and enlarged cervical lymph nodes. Sites of spread of medullary thyroid carcinoma include local lymph nodes in the neck, lymph nodes in the central portion of the chest (mediastinum), liver, lung, and bone. Spread to other sites such as skin or brain occurs but is uncommon. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「medullary thyroid cancer」の詳細全文を読む スポンサード リンク
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