In 75% of cases, the tumor is sporadic, with peak occurrence at 40–60 years of age, while in 25% it is hereditary and associated with the most common form of multiple endocrine neoplasia (MEN2A), which is MEN2B.As it is familial, itis now considered a variant of MEN2A, and it is transmitted in an autosomal dominant fashion [4]. This evidence concerns the gene RET and multiple endocrine neoplasia.