Multiple endocrine neoplasia type 1 and 2. Diagnostic features and molecular pathology 1997

Multiple endocrine neoplasia syndromes (MEN) encompass autosomal dominantly inherited diseases which are characterized by the syn-or metachrone development of neoplastic and hyperplastic neuroendocrine lesions in several glands of an affected patient. In MEN type 1 the parathyroids, endocrine pancreas and duodenum and the pituitary and in MEN type 2 the thyroid C-cells, adrenal medulla and parathyroids are involved. Due to the recent identification of the mu gene and RET protooncogene as MEN-1 and MEN-2, respectively, and the elucidation of the genetic defects in affected patients, direct mutational analysis of germline DNA allows for the unambiguous identification of gene carriers and therefore the discrimination of MEN-associated and sporadically occurring neuroendocrine tumors. This is especially helpful in the context of the fairly high de novo mutation rates in MEN, since the discrimination of familial and sporadic neuroendocrine lesions by conventional and immunohistochemical analyses is rather unreliable. While the development of neuroendocrine lesions in young patients, bilateral or multicentricer tumors and the combination of hyperplastic and neoplastic lesions are indicative for a MEN syndrome, such constellations may also occur coincidentally or in association with other inherited diseases. In this overview, most recent findings concerning pathogenesis, molecular features, clinics and therapeutic concepts of MEN-1 and 2 are summarized and discussed.