RET proto-oncogene mutation in a mixed medullary-follicular thyroid carcinoma

A case of a patient with an uncommon thyroid carcinoma, showing histological and immunohistochemical features of both follicular and parafollicular cells is described. Somatic point mutation (ATG to ACG heterozygotic mutation at codon 918) of the RET proto-oncogene was detected in tumor tissue, as confirmed by immunohistochemical expression of RET oncoprotein. Our findings suggest that constitutive RET proto-oncogene activation may be involved in the development of mixed medullary-follicular thyroid carcinoma. (C) 2001, Editrice Kurtis.