Multiple endocrine neoplasia (MEN) - Multiple endocrine neoplasia syndrome

Multiple endocrine neoplasia syndrome

Multiple endocrine neoplasia (MEN)

Definition

Multiple endocrine neoplasia is a group of inherited syndromes characterised by multiple tumours of endocrine glands.

Multiple endocrine neoplasia type I

Inherited in an autosomal dominant pattern. The function of the gene products are unknown but it is suggested that susceptible individuals inherit a gene defect from one parent, tumour growth occurs when the remaining copy of the gene is inactivated by so-matic mutation.

Tumours occur within the parathyroids in 90% (re-sulting in primary hyperparathyroidism), anterior pi-tuitary (pituitary adenomas) and pancre-atic islet cells. MEN I is defined as the presence of at least two of the three main tumour types.

Multiple endocrine neoplasia type II

Inherited in an autosomal dominant pattern with high penetrance. Mutations occur in the RET proto-oncogene.

Tumours include medullary carcinoma of the thyroid, phaeochromocytomas (may be bilateral or multiple) and parathyroid tumours.

Type IIb MEN may also have numerous mucosal neu-romas, intestinal ganglioneuromas and a Marfanoid appearance.

Management

Tumours are surgically removed wherever possible, how-ever recurrence is common. When an index case has been identified family members require screening either us-ing genetic probes (when the mutation is known) or with endocrine testing for glandular dysfunction.