Multiple Endocrine Neoplasia Syndromes

Multiple endocrine neoplasia (MEN) is characterized by the occurrence of tumors involving two or more endocrine glands within a single patient. Four major forms of MEN are recognized and referred to as MEN types 1-4, and each form is characterized by the development of tumors within specific endocrine tissues. Each form of MEN is typically inherited as an autosomal dominant syndrome but may occur sporadically; that is, without a family history, although this distinction between sporadic and familial cases may sometimes be challenging. In addition to MEN1-4, six other syndromes which are associated with multiple endocrine and other organ neoplasias (MEONs) are recognized. These include the hyperparathyroidism-jaw tumor (HPT-JT) syndrome, Von Hippel-Lindau disease, Carney complex (CNC), Neurofibromatosis type 1 (NF1), Cowden syndrome (CWD), and McCune-Albright syndrome. Each of these are typically inherited as autosomal dominant disorders, with the exception of McCune-Albright syndrome which is due to a mosaic expression of a postzygotic somatic GNAS mutation. Each MEN and MEONs syndrome is associated with skeletal disease that include osteoporosis, scoliosis, pseudoarthroses, long bone and spinal dysplasias, ossifying tumors, osteochondromyxomas, as well as metastatic involvement.