Prolactinoma and Adenomyosis - More than Meets the Eye: A Case Report

To report a case of adenomyosis in a woman with hyperprolactinemia which resolved after initiation of dopamine agonist therapy.

A 35-year-old woman with a history of Graves' disease was referred for evaluation of hyperthyroidism in March 2020. She was started on methimazole and thyroid function normalized. The patient also had a history of a pituitary microadenoma and was previously treated with cabergoline which was stopped after 12 months as she became pregnant.In July 2020, the patient began to have polymenorrhea. Hyperprolactinemia was thought to be an unlikely cause as it most often causes hypogonadotropic hypogonadism with amenorrhea. A pelvic ultrasound demonstrated a bulky uterus with adenomyosis. Gynecology recommended treating adenomyosis by lowering her prolactin levels. She was started on cabergoline 0.25 mg weekly in October 2021. Within 2 months of initiation of cabergoline, she had resolution of symptoms and radiological resolution of adenomyosis.

Prolactin has been implicated in the pathogenesis of adenomyosis, endometriosis and leiomyomas suggesting that a decrease in prolactin levels may suppress these lesions. The pathogenesis of adenomyosis has been related to direct prolactin effects in the promotion of gland/cell proliferation and function.

We conclude that prolonged elevation in prolactin may result in the development of adenomyosis and subsequent prolonged abnormal uterine bleeding. Dopamine agonists, like cabergoline, inhibit the synthesis and secretion of prolactin from the pituitary gland and may have a role in the management of adenomyosis in patients with hyperprolactinemia.