Prolactinoma: The “Breast Tumor” Not Found in the Breast

Prolactinoma: The “Breast Tumor” Not Found in the Breast

Continuing our series on nipple discharge – there are a few non-breast related causes which warrant discussion. Prolactinoma is a non-cancerous tumor of the brain which can cause milky discharge or leakage from both breasts.


Prolactinoma is a benign tumor of the brain that occurs in the pituitary gland. The pituitary gland is a small structure located in the central deep brain. It is a regulator of many bodily functions via the hormones it releases, including the stimulation of milk production for breastfeeding.


When the pituitary is abnormal, such as when there is a tumor or growth, it can cause hormone imbalance. In the case of prolactinoma, there are abnormal levels of the hormone prolactin circulating in the body. Prolactinomas are also associated with decreased levels of other hormones, including estrogen in women and testosterone in men.


Prolactin plays a crucial role in breast milk. When a woman is breastfeeding, the amount of prolactin in her circulation helps regulate the production of milk. When the pituitary misfires due to a prolactinoma it can cause the breasts to express milk even when not breastfeeding. 


These benign growths in the pituitary can also lead to other symptoms, and may not result in breast discharge in everyone. Other symptoms related to these tumors are often from enlargement of the gland and compression of adjacent important structures like the nerves that run to the eyes. This can result in decreased vision. These benign growths may be treated with medications, restoring prolactin levels to normal, or may be treated with surgery.


So if you have nipple discharge, it is important to discuss with your doctor. That said, thanks to modern medicine, discharge can often be treated, getting you back on the road to your best possible health!




Image credit: Prolactinoma-art by National Endocrine and Metabolic Diseases Information Services, NIH via Wikimedia Commons Copyright Public Domain

Originally published 1/24/14 on