Multiple endocrine neoplasia types
There are several types of multiple endocrine neoplasia. The two most common types are multiple endocrine neoplasia type 1 (MEN1) and multiple endocrine neoplasia type 2 (MEN2).
Multiple endocrine neoplasia type 4 (MEN4) is rare. This type has similar symptoms to MEN1 but has a different genetic cause.
People with MEN1 develop tumors or excessive growth of two or more endocrine glands. These tumors are typically benign (noncancerous). The most frequently affected glands are:
- Parathyroid gland: Almost all people with MEN1 develop parathyroid tumors. These tumors cause the gland to produce too much parathyroid hormone, which often raises blood calcium levels.
- Pancreas: Many people with MEN1 develop pancreatic neuroendocrine tumors. These tumors affect the islet cells of the pancreas. Pancreatic NETs often cause production of too much stomach acid, which may lead to ulcers. Approximately 1 in 3 pancreatic NETs are cancerous.
- Pituitary gland: Some people with MEN1 also develop tumors on the pituitary gland. These tumors can cause the gland to produce too much of a few different hormones, including prolactin, growth hormone or corticotropin.
Less frequently, MEN1 may cause adrenal gland tumors, thyroid gland tumors or neuroendocrine tumors (NETs) in other organs. People assigned female at birth with MEN1 are also at increased risk of developing breast cancer.
MEN2 has two subtypes: MEN2A and MEN2B (formerly called MEN3).
Multiple endocrine neoplasia type 2A
Approximately 95 percent of people with MEN2 have the MEN2A subtype. MEN2A typically affects these glands:
- Thyroid: At least 90 percent of people with MEN2A develop medullary thyroid cancer at some point.
- Adrenal: About half of people with MEN2A develop pheochromocytoma, a type of adrenal tumor.
- Parathyroid: Less than 25 percent of people with MEN2A have parathyroid involvement. When MEN2A affects the parathyroid, it may cause hyperplasia (increased gland size) or a noncancerous tumor called parathyroid adenoma.
People with this subtype may also experience an itchy skin condition called cutaneous lichen amyloidosis. A small number of people with MEN2A may have a congenital condition called Hirschsprung's disease, which affects the nerves of the large intestine.
Multiple endocrine neoplasia type 2B
This rare subtype affects approximately 5 percent of people with MEN2. People with MEN2B may experience:
- Medullary thyroid cancer: At least 98 percent of people with MEN2B develop this type of tumor. Medullary thyroid cancer develops much earlier in people with MEN2B, typically in childhood or early adulthood.
- Pheochromocytoma: About 50 percent of people with MEN2B develop this type of adrenal tumor. Pheochromocytomas typically aren't cancerous, but they can cause other problems such as high blood pressure.
- Mucosal neuromas: Approximately 95 percent of people with MEN2B have this type of benign nerve tumor. Mucosal neuromas may develop on the tongue, lips, eyes or gastrointestinal tract. GI nerve tumors frequently cause digestive problems.
- Skeletal anomalies: Many people with MEN2B develop bone, joint or muscle problems. They may also have physical features such as a curved spine, long limbs and loose joints.
- Skin and eye changes: People with MEN2B may have thicker eyelids and lips. They may develop lumps or bumps on the lips, eyelids or tongue. Some people may not produce tears when they cry.