Multiple endocrine neoplasia is a group of rare, inherited disorders that involve the development of tumors (benign or malignant) or excessive growth in several endocrine glands. It can affect individuals of any age, from young infants to the elderly, and is caused by mutations in certain genes (MEN1, RET and CDKN1B) that are usually inherited from the parents and tend to run in families.
There are three types of multiple endocrine neoplasia according to the pattern of the syndrome, as follows:
- Type 1: Tumor or excessive growth in at least two of the following - parathyroid gland, pituitary gland, thyroid gland, adrenal glands, and pancreas - due to a mutation in MEN1 gene.
- Type 2A: Tumor or excessive growth in at least two of the following -thyroid gland, adrenal glands, and parathyroid gland - due to a mutation in RET gene.
- Type 2B: Presence of medullary thyroid cancer, pheochromocytoma or neuromas, usually due to spontaneous mutation in the CDKN1B gene that is not inherited.
Type 1 is the most common and affects approximately 1 in 30,000 people and type 2A affects approximately 1 in 35,000 people. The incidence of type 2B is unknown.
The symptoms of multiple endocrine neoplasia depend on the type of disease and the endocrine glands that are affected by the tumor growth, as the normal function of the gland may be altered by the tumor. In most cases, the affected endocrine gland produces more hormones than usual, leading to excessive levels and effect of the hormones.
A tumor of the parathyroid gland, which is particularly common in type 1 multiple endocrine neoplasia causes excessive production of parathyroid hormone and symptoms of hyperparathyroidism and sometimes leads to the development of kidney stones.
An itchy skin condition known as cutaneous lichen amyloidosis may affect individuals with type 2. Additionally, medullary thyroid cancer is also common in these individuals.
Patients with type 3 multiple endocrine neoplasia usually develop symptoms early in age and may develop neuromas visible as bumps on the lips, tongue, mouth, and eyelids. It may also cause gastrointestinal symptoms, such as constipation or diarrhea if the digestive tract is affected.
The symptoms are very varied according to the type and extent of the glands affected and may include:
- Abdominal pain
- Constipation or diarrhea
- Depression and anxiety
- Decreased libido
- Fatigue and weakness
- Loss of appetite and weight
In individuals with a family history of multiple endocrine neoplasia or those with evidence of one tumor typical of the syndrome, genetic screening tests are useful to detect the disease.
Additionally, blood and urine tests can investigate the levels of hormones in the body and establish the extent of hormonal changes that may be causing symptoms of the condition. Diagnostic imaging techniques such as ultrasound, magnetic resonance imaging (MRI), and computed tomography (CT) scans are also useful to determine the location of the tumor for treatment.
There is no cure available for multiple endocrine neoplasia. However, there are several management techniques to control the production of hormones affected by the tumor growth and reduce the symptoms of the condition.
Each affected endocrine is usually treated individually to manage the symptoms associated with that gland. Removal of the tumor or the entire gland (e.g., the thyroid gland) may be required to manage the symptoms. Following this, hormone replacement therapy is often needed to maintain normal levels of the hormones in the body, which is a lifelong treatment.