Prolactin-producing uterine leiomyomas are very rare. Although hyperprolactinemia rapidly improves after removal of such leiomyomas, no preoperative diagnostic test has been established for prolactin-producing uterine leiomyomas. A 45-year-old Japanese woman, gravida 3 para 3, was referred to our hospital for further examination of hyperprolactinemia resistant to a dopamine agonist. A pituitary prolactinoma was undetectable by brain magnetic resonance imaging. A bromocriptine loading test revealed an increased serum prolactin concentration after loading. Examination for the detection of an ectopic prolactinoma revealed a 9.0 cm diameter uterine leiomyoma that had measured 6.6 cm in diameter about six months before the first visit to our hospital. The hyperprolactinemia rapidly improved after hysterectomy. A prolactin-producing uterine leiomyoma should be considered as a possible cause of hyperprolactinemia resistant to dopamine agonists. Responsiveness to dopamine agonists; deterioration of hyperprolactinemia may be diagnostic for prolactin-producing uterine leiomyomas, although further research is required.
Keywords: Bromocriptine; hyperprolactinemia; hysterectomy; prolactinoma; uterine leiomyoma.