The etiology of these tumors remains unknown for many patients, but it has been observed that sporadic forms of adenoma are commonly related to mutations in the cyclin D1/PRAD1 gene, while the hereditary forms have been found in families affected by diseases, such as Multiple Endocrine Neoplasia type 1 or 2 (MEN 1 or 2) and Familial Hypocalciuric Hypercalcemia (FHH) [4]. This evidence concerns the gene CCND1 and multiple endocrine neoplasia.