Multiple endocrine neoplasia

Multiple endocrine tumors have been recognized from the beginning of this century, when a case of pituitary gland adenoma with concomitant parathyroid hyperplasia was reported [1]. After other reports of individual cases, the familial basis of this clinical entity was documented [2], and this led to the definition of the three main patterns of the disease. Multiple endocrine neoplasia type 1 (MEN-1, or Wermer syndrome) is characterized by a combination of pancreatic islet, pituitary, and parathyroid tumors; in MEN-2A (or Sipple syndrome), there is an association of thyroid (medullary carcinoma, MTC), adrenal medullary, and parathyroid tumors; MEN-2B (also called MEN-3 or multiple mucosal neuroma syndrome), in addition to the features of MEN-2A, shows an unusual phenotype, which includes eye and oral ganglioneuromas, a marfanoid habitus, and facial and skeletal involvement [3]. Finally, some authors described as MEN-4 (MEN of mixed type) the clinical condition featured by some overlap between MEN-1 and MEN-2 [4]. An outline of organs involved, the main type of tumors, and the symptoms occurring in various MEN syndromes are shown in Table 1.