Multiple endocrine neoplasia: Pathology review

Two individuals came in for genetic testing based on recommendations from their primary care physicians. The first one is 24 year old Kurt, who was previously diagnosed with Zollinger-Ellison syndrome and also has an adenoma in one of his parathyroid glands. On the clinical examination, doctors observed that he has gynecomastia. His mother also has parathyroid adenomas. The other one is 19 year old Courtney, who was previously diagnosed with parathyroid hyperplasia and pheochromocytoma. Her father has recently been diagnosed with thyroid medullary cancer.

Although their presentation and family history differ, both people have multiple endocrine neoplasias, or MEN for short. These are a group of inherited diseases which cause tumors to grow in the endocrine glands of the body. The endocrine glands affected in multiple endocrine neoplasia are the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, and the pancreas. So in multiple endocrine neoplasias, there are tumors that form in these glands that lead to overproduction of hormones.

Multiple endocrine neoplasias are caused by genetic mutations in one of two genes: either MEN1 or RET, which codes for receptor tyrosine kinase. For your exams, remember that both of these genes have a dominant inheritance pattern, so only one copy of the mutated gene is needed to get the disease.

Okay, let’s start with the MEN1 gene that is found on chromosome 11 and codes for a tumor suppressor protein called menin, which - under normal circumstances - stops a cell from dividing uncontrollably. MEN1 mutations cause MEN type 1. For your tests, you absolutely have to know that there are three types of tumors associated with MEN type 1: parathyroid, pancreatic, and pituitary.

The most common tumor is a parathyroid adenoma. Increased parathyroid hormone production causes increased bone breakdown, which leads to hypercalcemia. The clinical manifestations of hypercalcemia can be recalled by the mnemonic: “Stones, bones, groans, and moans”. Stones refers to the calcium kidney stones. Bones refers to bone pain that results from the increased resorption of bone in hyperparathyroidism. Groans refers to the abdominal complications in hypercalcemia:including peptic ulcer disease, pancreatitis, and constipation. Lastly, moans refers to the psychiatric symptoms of hypercalcemia, such as altered mental status and psychosis.