Multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type I (MEN1), also known as Wermer syndrome, is an autosomal dominant genetic disease that results in proliferative lesions in multiple endocrine organs, particularly the pituitary gland, islet cells of the pancreas and parathyroid glands. 

There are other multiple endocrine neoplasia syndromes and these are discussed separately. 

Clinical presentation

Primary hyperparathyroidism is the commonest presentation, followed by pancreatic islet cell tumour with associated hypersecretion syndromes; gastrinomas are most common and associateassociated with Zollinger-Ellison syndrome ⁷. 

Pathology

The abnormality is related to a tumour suppressor gene located in chromosome 11q13. MEN type I is an autosomal dominant syndrome characterised by ^1-7:

• pituitary adenomas
  • prolactinoma (most common)
  • 30% of patients
• islet cell tumours of the pancreas
  • gastrinoma (most common) followed by glucagonoma
  • 50-80% of patients
  • a significant cause of mortality
• proliferative parathyroid gland lesions ⁷
  • parathyroid hyperplasia (most common)
    • hyperparathyroidism is seen in 80-95% of patients
  • parathyroid adenoma
  • parathyroid carcinoma (rare)

Handy mnemonics for recalling MEN type I: 

• PPP or PiParPanc

Associations

In addition to the aforementioned characteristic lesions involving the pituitary, parathyroid and pancreas, numerous other lesions are encountered with greater frequency in patients with MEN1. These include: 

• lipomas
• angiofibromas
• adrenal cortical lesions
  • adrenal adenomas
  • adrenocortical hyperplasia
  • cortisol-secreting adenomas
  • adrenal carcinomas (rare)
• carcinoid tumours
• hepatic focal nodular hyperplasia ⁵

Treatment and prognosis

Treatment is directed to each individual manifestation. These are therefore discussed separately.

Pancreatic malignancy is the leading cause of mortality in MEN type I. 

History and etymology

MEN1 was first characterised by P Wermer et al. in 1954 ³.

See also

• MEN1 (Wermer syndrome)
• MEN2
  • MEN2a (Sipple syndrome)
  • MEN2b (mucosal neuroma syndrome)
  • familial medullary thyroid carcinoma
• MEN4
• Carney complex