What is a prolactinoma?
A prolactinoma is a growth, or tumor, on the pituitary gland that causes the pituitary to produce too much of the hormone prolactin. Prolactin is produced by the pituitary gland to stimulate the production of breast milk in women during pregnancy and after a baby is born.
Prolactinomas are the most common type of pituitary tumor. They occur most frequently in adult women, but do occur, more rarely, in children and adolescents, both boys and girls.
Prolactinomas are usually small and benign, which means they are generally non-cancerous. Most do not grow, but some can become large enough to put pressure on the nerves and brain tissue near the pituitary gland, including the optic nerves.
Causes of prolactinoma
In some cases, prolactinoma is associated with inherited conditions that lead to the formation of tumors on the pituitary and other glands. In other cases, a cause cannot be established.
Researchers are working to understand whether prolactinomas and other pituitary tumors are caused by genetic mutations, hormonal abnormalities, or a combination of these and other factors.
Signs and symptoms of prolactinoma
Symptoms of prolactinoma vary with the age and gender of the child, and with the size of the tumor.
Symptoms may include:
- Delayed puberty in both boys and girls
- Irregular or no menstrual periods in girls
- Hypogonadism (decreased production of sex hormones)
- Milky discharge from the breasts, not associated with pregnancy or nursing
- Vision problems, such as double vision or a narrowed field of vision
Prolactinomas tend to become larger in boys, so the symptoms of vision problems and headaches are more common in boys who have the condition. These symptoms are caused by pressure on the brain or the optic nerves.
Large prolactinomas can put pressure on the pituitary gland and interfere with the production and release of other hormones. When this happens, other symptoms may appear, including slowed growth.
The excess production of prolactin caused by prolactinomas can also lead to loss of bone density, though this does not typically lead to more frequent broken bones in children and adolescents.
Testing and diagnosis for prolactinoma
The doctor’s first steps will be to conduct a physical exam and obtain a complete medical history. If the information from the exam and history suggest the possibility of prolactinoma, the doctor may order additional diagnostic tests. These might include:
- Blood tests to check for abnormal levels of prolactin and other hormones
- Vision tests to check for signs of pressure on the optic nerves
- Brain imaging using magnetic resonance imaging (MRI) or computed tomography (CT) scan
- Vision tests, especially if a large tumor is found through brain imaging, to check for signs of pressure on the optic nerves
Treatment for prolactinoma
Prolactinomas are treated with medications called dopamine agonists, which reduce the secretion of prolactin and, in many cases, shrink the size of the tumor.
Surgery to remove the tumor may be considered, but only if medication doesn’t work or causes serious side effects. Surgery is rarely used in the treatment of prolactinomas because the dopamine agonists are so effective.
Most people with prolactinomas are able to control prolactin levels with dopamine agonists and eliminate the negative effects of the tumors. Most children and adolescents with the condition grow into adults with normal sexual functions, including, for women, the ability to have a healthy pregnancy.
Periodic follow-up is required to check the status of the tumor, including imaging and checking levels of prolactin.
If dopamine agonists are taken to control prolactin levels and shrink the tumor, the medication might be needed for life. In some cases, if the medication is stopped, the prolactin level may rise back to abnormal levels and the tumor may increase in size. In other cases, judiciously reducing medications may be an option.
Why choose CHOP?
Children with neuroendocrine tumors often require care from many pediatric specialties.
The Neuroendocrine Center at Children’s Hospital of Philadelphia offers families a coordinated and multidisciplinary approach to treatment for neuroendocrine disorders. Our team combines the expertise of pediatric endocrinologists, neuro-oncologists, neuro-surgeons, neuro-ophthalmologists, neuro-radiologists and pathologists.
All our team members have vast experience in the treatment of complex neuroendocrine conditions.
Reviewed by Shana E. McCormack, MD, MTR, Craig Alter, MD