Prolactinoma

Prolactinoma is a generally benign (noncancerous) tumor that forms in your pituitary gland and makes more prolactin — a hormone — than you need. About 50% of pituitary tumor (pituitary adenoma) cases are prolactinomas, making them the most common type of pituitary tumor.

Prolactin is mainly responsible for the development of mammary glands within breast tissue and lactation. It contributes to several other bodily processes as well. Prolactinomas cause higher-than-normal levels of prolactin in your blood (hyperprolactinemia), resulting in infertility and other issues.

The thought of having a tumor so close to your brain can be unsettling. You may breathe a little easier knowing that prolactinomas aren’t life-threatening. But they can cause unwanted health issues, so it’s important to seek care if you develop symptoms.

Types of prolactinomas

There are two main types of prolactinomas based on their size:

• Microprolactinomas: These tumors are very small — less than 1 centimeter or 3/8 of an inch in diameter. They represent at least half of prolactinoma cases and more commonly affect women and people assigned female at birth (AFAB).
• Macroprolactinomas: These tumors are larger than 3/8 of an inch or 1 centimeter in diameter. They’re more common in men and people assigned male at birth (AMAB) and tend to occur at an older age.

Among people with prolactinomas, as many as 60% of people AMAB have macroprolactinomas, while 90% of people AFAB have microprolactinomas.