Multiple endocrine neoplasia (MEN) II

  • Definition
    • Multiple endocrine neoplasia, type II (MEN II) is a disorder passed down through families in which one or more of the endocrine glands are overactive or form a tumor. Endocrine glands most commonly involved include:

      • Adrenal gland (about half the time)
      • Parathyroid gland (20% of the time)
      • Thyroid gland (almost all of the time)

      Multiple endocrine neoplasia (MEN I) is a related condition.

  • Alternative Names
    • Sipple syndrome; MEN II; Pheochromocytoma - MEN II; Thyroid cancer - pheochromocytoma; Parathyroid cancer - pheochromocytoma

  • Causes
    • The cause of MEN II is a defect in a gene called RET. This defect causes many tumors to appear in the same person, but not necessarily at the same time.

      Involvement of the adrenal gland is most often with a tumor called a pheochromocytoma.

      Involvement of the thyroid gland is most often with a tumor called medullary carcinoma of the thyroid.

      Tumors in the thyroid, adrenal, or parathyroid glands may occur years apart.

      The disorder may occur at any age, and affects men and women equally. The main risk factor is a family history of MEN II.

      There are 2 subtypes of MEN II. They are MEN IIa and IIb. MEN IIb is less common.

  • Symptoms
  • Exams and Tests
  • Treatment
    • Surgery is needed to remove a pheochromocytoma, which can be life-threatening due to the hormones it makes.

      For medullary carcinoma of the thyroid, the thyroid gland and surrounding lymph nodes must be totally removed. Thyroid hormone replacement therapy is given after surgery.

      If a child is known to carry the RET gene mutation, surgery to remove the thyroid before it becomes cancerous is considered. This should be discussed with a physician who is very familiar with this condition. It would be done at an early age (before age 5) in people with known MEN IIa, and before age 6 months in people with MEN IIb.

  • Outlook (Prognosis)
    • Pheochromocytoma is most often not cancerous (benign). Medullary carcinoma of the thyroid is a very aggressive and potentially fatal cancer, but early diagnosis and surgery can often lead to a cure. Surgery does not cure the underlying MEN II.

  • Possible Complications
    • The spread of cancerous cells is a possible complication.

  • When to Contact a Medical Professional
    • Call your health care provider if you notice symptoms of MEN II or if someone in your family receives such a diagnosis.

  • Prevention
    • Screening close relatives of people with MEN II may lead to early detection of the syndrome and related cancers. This may allow for steps to prevent complications.

  • References
    • National Comprehensive Cancer Network. Clinical practice guidelines in oncology: neuroendocrine tumors. National Comprehensive Cancer Network; 2014. Updated May 25, 2016. Version 1.2015. Accessed April 6, 2016.

      Nieman LK, Spiegel AM. Polyglandular disorders. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 231.

      Tacon LJ, Learoyd DL, Robinson BG. Multiple endocrine neoplasia type 2 and medullary thyroid carcinoma. In: Jameson JL, De Groot LJ, de Kretser DM, et al, eds. Endocrinology: Adult and Pediatric. 7th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 149.