Endocrine Abstracts

Multiple endocrine neoplasia (MEN) syndromes are classically defined as the occurrence of two or more endocrine tumours in a patient, and include two major forms, characterized by development of tumours within specific endocrine glands, referred to as type 1 (MEN1) and type 2 (MEN2). These disorders are due to mutations in the MEN1 gene in MEN1 (parathyroid, pituitary or pancreatic tumours), and in the RET gene in MEN2 (which comprises three types: MEN2A with medullary thyroid carcinomas, pheochromocytomas, and hyperparathyroidism; MEN2B with medullary thyroid carcinomas, pheochromocytomas, mucosal neuromas, ganglioneuromas and marfanoid habitus; and isolated familial medullary thyroid carcinoma). Additionally, CDKN1B gene mutations are detected in MEN 4 (parathyroid and pituitary tumours), the rarest form of MEN diseases. However, tumours occurring in MEN syndromes may also have a non-endocrine origin such as lipomas and facial angiofibromas in MEN1 syndrome. In addition, there are other hereditary endocrine syndromes in which there is only one type of endocrine tumour occurring either in an isolated form (familial isolated pituitary adenomas) or, eventually, associated with tumours from other tissues (hyperparathyroidism-jaw tumour syndrome and paraganglioma/pheochromocytoma syndrome). On the other hand, endocrine neoplasias may also be a component of hereditary syndromes characterized by a predominance of non-endocrine tumours such as Cowden syndrome, Carney complex, familial adenomatous polyposis or von-Hippel–Lindau disease.

Hereditary endocrine neoplasias are usually inherited as an autosomal dominant trait and are due to mutations in tumour suppressor genes, except for MEN2/FMTC in which the causative gene, the RET gene, is a proto-oncogene.

Individually, each of these syndromes has a low incidence/prevalence but, due to their multiplicity, Endocrinologists, in particular those working in referral centers for endocrine tumours, are frequently requested to evaluate and treat patients with such neoplasias.

Illustrative cases of some of these syndromes will be presented and discussed in this MTE session.