Ectopic Prolactin Secretion from a Uterine Leiomyoma

Ectopic hormone production is well recognized, but ectopic production of prolactin has been reported infrequently. We report here the case of a 47-year-old woman who had hyperprolactinemia (213-224 ng/mL) causing galactorrhea and hypogonadism. Cabergoline treatment, 1.0 mg twice a week, did not lower the prolactin level at all, but excision of a large uterine leiomyoma corrected the hyperprolactinemia and the hypogonadism. The excised leiomyoma tissue exhibited immunostaining for prolactin, confirming by this method for the first time that a uterine leiomyoma was the cause of hyperprolactinemia. This case illustrates the need to consider an ectopic source of prolactin in a patient who has hyperprolactinemia that is not associated with a large sellar mass and is completely resistant to cabergoline.