Multiple Endocrine Neoplasia Type 1

In: Endotext [Internet]. South Dartmouth (MA):, Inc.; 2000–.


MEN-1 syndrome is a rare autosomal dominant disease with a high degree of penetrance, characterized by hyperplasia and/or neoplasia of the parathyroid, pancreatic islet cells, and pituitary, usually prolactinomas. Hyperparathyroidism occurs in about 90%, pNETs in 60% and pituitary adenomas in 40% of patients. The most common pNET is a gastrinoma frequently found in the duodenum but others include non-functioning tumors, vipomas, glucagonomas, somatostatinomas and Ppomas. Tumors may function synchronously or meta-synchronously. More than one syndrome may occur in the same patient and metastases may secrete different hormones. In women with MEN-1 breast carcinoma is increased 2.8 fold. MEN-1 is a tumor suppressor gene on (11q13), and there are more than 300 different MEN-1 germ line mutations and about 20 % of MEN kindred have no mutation. Tumors have loss of zygousity and the allelic loss is from the unaffected parent. The protein encoded is menin that binds to double stranded DNA and is a tumor suppressor. MEN-1 gene mutations are also found in non-syndromic tumors. Diagnosis of MEN requires presence of the gene mutation without signs or symptoms, an individual with the disease and the same disease in a 1st degree relative, or an individual who has two or more of the clinical syndromes. Biochemical testing should include PTH, prolactin, fasting gastrin and a secretin/calcium provocative test. Tumor localization requires endoscopic ultrasound, Octreoscan and PET/CT using Ga-68-Dota(-D-)-Phe(1)-Tyr(3)-octreotide (Ga-68-DOTATOC) to image neuroendocrine tumors with a reported sensitivity and specificity of 91.7% and 93.5%, respectively have altered management in 47.6% of MEN1 patients However this has not been found uniformly. Surgical management of the parathyroid usually involves total parathyroidectomy with implant of parathyroid in the forearm, allowing local excision in the case of recurrence. Localizing the pancreatic tumors requires THPVS and only the producing tumor(s) should be removed. The larger the tumor the more likely are metastasis! In general prognosis is good and the 15 year survival is 93%. Symptoms and secretions can be controlled. Mortality has shifted to thymic and carcinoid tumors. For complete coverage of this and related areas of Endocrinology, please visit our free online textbook, WWW.ENDOTEXT.ORG.

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