Abstract

Medullary thyroid carcinoma (MTC) is the third most prevalent thyroid cancer and the most invasive form. This malignancy could be presented either in a sporadically or a familial pattern. Although the majority of cases with this disease are presented sporadically, familial screening is of great necessity in every MTC case since of all heritable cancers, MTCs are the most common malignancies. Therefore, after the familial screening of MTC patients using clinical symptoms along with paraclinical tools, the present study identified 19 familial medullary thyroid carcinoma (FMTC) cases in one family. Since most FMTCs are associated with multiple endocrine neoplasia’s (MEN's) syndrome, it has attracted a great deal of scientific attention. This syndrome was ruled out herein through both genetic and clinical testing in these individuals. Thus, due to the scarcity of the familial form of this disease, the significant number of MTC in a family, and the absence of MEN syndrome in these people, we decided to report 19 patients with MTC in the same family without MEN’s syndrome from southwest of Iran; this report emphasizes the necessity of familial screening even in the absence of the MEN's syndrome. © 2023, Shiraz University of Medical Sciences. All rights reserved.