Novel Ret Mutations in Macedonian Patients with Medullary Thyroid Carcinoma: Genotype-Phenotype Correlations/ Нови Ret-Мутации Кај Македонски Пациенти Со Медуларен Карцином На Тироидната Жлезда: Генотипско-Фенотипски Корелации

Medullary thyroid carcinomas (MTCs) are rare neoplasms comprising 2-10% of all thyroid malignnancies. More than 75% are sporadic tumors and the remainder is familial and MEN2 related. Both sporadic and syndromic MTCs frequently show mutations in the RET proto-oncogene. It has been noted that some MTC cases present an indolent, and some an aggressive clinical course. Ki-67 expression is generally low, with documented exceptions, whereas high...