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Multiple Endocrine Neoplasia Type 4 (MEN4)

Rare hereditary endocrine tumor syndrome caused by germline CDKN1B (p27Kip1) mutations characterized by parathyroid adenomas, pituitary adenomas, and various neuroendocrine tumors with later onset and milder phenotype than MEN1.

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

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This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Endokrinoloji department. Book Appointment →

What is Multiple Endocrine Neoplasia Type 4 (MEN4)?

MEN4 is a tumor predisposition syndrome inherited in autosomal dominant pattern caused by heterozygous loss-of-function mutations in CDKN1B encoding the cell-cycle inhibitor p27Kip1, identified in approximately 1.5–3.7% of MEN1-like patients without MEN1 mutation.

p27Kip1 normally inhibits cyclin-dependent kinase activity at the G1/S transition; reduced p27 leads to unchecked cell-cycle progression in endocrine glands, fostering tumor formation in parathyroid, pituitary, and other neuroendocrine tissues.

Compared with MEN1, MEN4 features later age at onset (commonly 40–60 years), less aggressive course, lower penetrance, and rare gastroenteropancreatic neuroendocrine tumors; diagnosis requires germline CDKN1B sequencing in MEN1-mutation-negative patients with multiple endocrine tumors.

Symptoms

Primary hyperparathyroidism in 80–90% — fatigue, kidney stones, bone pain, depression, hypercalcemia
Pituitary adenoma in 30–40% — secreting (acromegaly, hyperprolactinemia, Cushing) or non-functioning with mass effect
Pancreatic or duodenal neuroendocrine tumors (less common than MEN1) — gastrinoma with peptic ulcers, insulinoma with hypoglycemia
Adrenal lesions, thyroid carcinoma, neuroendocrine cervical or bronchial tumors (rare)
Reproductive system tumors and gastric carcinoid in some kindreds
Family history with delayed onset and lower lifetime cancer risk than MEN1

Risk Factors

Germline CDKN1B mutation, autosomal dominant inheritance
Family history of MEN1-like phenotype with negative MEN1 sequencing
Multiple endocrine tumors at later age than MEN1 typical onset
Female sex slightly more common; reproductive system tumors reported
First-degree relatives of confirmed MEN4 patients require predictive testing
No known modifiable environmental risk factors

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Multiple endocrine tumors with negative MEN1 testing — referral for CDKN1B genetic testing in specialized endocrine genetics clinic
  • Primary hyperparathyroidism with pituitary adenoma at any age — clinical genetics evaluation
  • First-degree relative of MEN4-confirmed proband — predictive testing and surveillance from age 30
  • Cushing or acromegaly features in known MEN4 — pituitary MRI and biochemical workup
  • New abdominal symptoms (peptic ulcer, hypoglycemia) in MEN4 — pancreatic neuroendocrine tumor screening

Treatment Methods

01
Primary hyperparathyroidism — selective parathyroidectomy of enlarged glands or subtotal parathyroidectomy depending on multiglandular involvement and surgeon preference
02
Pituitary adenoma — transsphenoidal surgery for sight-threatening or hormonally-active tumors; medical therapy with cabergoline (prolactinoma), somatostatin analog (acromegaly), or pasireotide (Cushing)
03
Pancreatic and duodenal neuroendocrine tumors — surgical resection, somatostatin analogs, peptide receptor radionuclide therapy (PRRT), or systemic therapy depending on functional status, size, and metastasis
04
Periodic surveillance: annual calcium and PTH; annual prolactin, IGF-1, and 24-hour urine cortisol; pituitary MRI every 3–5 years; abdominal imaging or 68Ga-DOTATATE PET as indicated
05
Genetic counseling for index patient and relatives; cascade testing of first-degree relatives; psychological support for asymptomatic carriers

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.