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MEDULLARY THYROID CARCINOMA Medullary thyroid carcinoma accounts for 5% to 8% of all thyroid cancers. It is a C-cell, calcitonin-producing tumor that contains amyloid or an amyloid-like substance. In addition to calcitonin, it may elaborate or secrete other peptides and amines such as carcinoembryonic antigen, serotonin, neurotensin, and a high-molecular-weight adrenocorticotropic hormone-like peptide. These substances may result in a carcinoid-like syndrome with diarrhea and Cushing’s syndrome, especially when widely metastatic tumor is present. Most medullary cancer of the thyroid is sporadic (about 70% to 80%), but it can also be transmitted in a familial pattern in 20% to 30% of cases. This tumor or its precursor, C-cell hyperplasia, occurs as a part of the multiple endocrine neoplasia type 2A (MEN2A) and type 2B (MEN2B) syndromes 45 (Table 3 and Fig. 14); or, rarely, as part of the familial medullary thyroid cancer syndrome. The MEN2 syndromes are transmitted as an autosomal-dominant trait, so 50% of the offspring would be expected to have this disease. Mutations of the ret oncogene on chromosome 10 have been found to be the cause of the MEN2 syndromes. 46 These defects are germ-line mutations and can therefore be found in blood samples. All patients with medullary thyroid carcinoma should be screened for hyperparathyroidism and pheochromocytoma. 47
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This note was uploaded on 11/22/2011 for the course BSC BSC1085 taught by Professor Sharonsimpson during the Fall '10 term at Broward College.

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