Multiple endocrine neoplasia

Multiple endocrine neoplasia (MEN) describes the occurrence of tumours affecting two or more endocrine glands in one patient. Two main forms are recognized: MEN type 1 (MEN1) and type 2 (MEN2). MEN1 is characterized by the combined occurrence of parathyroid, pituitary and pancreatic neuroendocrine tumours, whereas MEN2 features medullary thyroid cancer in association with phaeochromocytoma and parathyroid tumours. Although both MEN1 and MEN2 are autosomal dominant disorders, they have contrasting molecular aetiologies: MEN1 results from inactivating germline mutations of the MEN1 tumour suppressor gene, whereas MEN2 results from activating mutations in the RET proto-oncogene. The clinical features arising in each condition relate to the location of tumour development and/or hormonal hypersecretion, while treatment approaches aim to minimize morbidity and mortality, and preserve quality of life. Genetic testing is a key component of management, not only to confirm the diagnosis in affected patients, but also to identify family members who are at risk of disease but may be asymptomatic. It is recommended that patients 'at risk' of developing MEN1 and MEN2 (i.e. mutation carriers) undergo periodic clinical, biochemical and radiological surveillance to enable the early identification and/or treatment of tumours. Here, a brief overview of MEN1 and MEN2 is provided.