Successful management of refractory hyperprolactinemia secondary to ectopic prolactin-secreting disseminated peritoneal leiomyomatosis via surgical resection and postoperative leuprorelin therapy: a rare case report.

Background: Hyperprolactinemia is commonly caused by pituitary prolactinomas or medications and is typically managed with dopamine agonists (DAs). However, ectopic prolactin secretion from non-pituitary sources is rare and often unresponsive to medical therapy. Disseminated peritoneal leiomyomatosis (DPL), a benign condition characterized by diffuse intra-abdominal smooth muscle nodules, has not been previously reported as a source of ectopic prolactin production. The pathogenesis of DPL remains unclear, and no standardized treatment exists. Here we report a rare case of hyperprolactinemia in a female patient caused by DPL, who was successfully managed by surgical resection and postoperative leuprorelin therapy. Case Description: An 18-year-old female presented with amenorrhea, galactorrhea, and abdominal distension 17 months after open myomectomy. Initial brain magnetic resonance imaging (MRI) showed a possible microadenoma, and serum prolactin was >200 ng/mL. She received bromocriptine (up to 5 mg/day) for 6 months without response. Abdominal MRI revealed diffuse pelvic and abdominal infiltrative lesions, prompting exploratory laparotomy. Intraoperatively, multiple peritoneal and omental nodules consistent with DPL were identified. As much as possible, the nodules were resected to minimize residual disease. Postoperatively, prolactin normalized immediately. Immunohistochemistry confirmed prolactin expression in the lesions, along with weak prolactin receptor (PRLR) positivity. Adjuvant leuprorelin (3.75 mg monthly) was administered for 6 months. At follow-up, the patient remained asymptomatic with normal prolactin levels and no recurrence. Conclusions: This case demonstrates that DPL can cause ectopic hyperprolactinemia resistant to DAs. Surgical resection leads to rapid hormonal normalization, and gonadotropin-releasing hormone agonists (GnRH-a) therapy may prevent recurrence. Clinicians should consider extrapituitary prolactin-secreting lesions in patients with treatment-refractory hyperprolactinemia. Genetic evaluation may further elucidate the pathogenesis of such rare entities.