Persistent hyperprolactinemia after multimodal therapy in a pituitary macroadenoma: a case report

Abstract

Pituitary macroadenomas may present with reproductive disturbances that mimic physiological conditions such as pregnancy, thereby delaying diagnosis. A 33-year-old woman (G3P3A0) with previously regular menstrual cycles developed secondary amenorrhea after marriage and was initially presumed to be pregnant; repeated pregnancy tests and pelvic ultrasound examinations were negative. Hyperprolactinemia persisting for approximately two years eventually prompted pituitary imaging, which revealed a 2.9 × 2.5 × 1.9 cm cystic sellar–suprasellar macroadenoma. Because the preoperative prolactin concentration (90.23 ng/mL) was only moderately elevated relative to tumor size, stalk-effect hyperprolactinemia from a non-functioning adenoma was considered, and craniotomy with partial resection was performed in January 2024. Histopathology showed a benign pituitary adenoma; immunohistochemistry was not available. Postoperative computed tomography showed a residual hemorrhagic intrasellar lesion, subdural hematoma, subarachnoid hemorrhage, and cerebral edema, without neurological deficit. Prolactin decreased to 36.59 ng/mL in February 2024, normalized to approximately 23 ng/mL on bromocriptine 2.5 mg/day with resumption of menses, and the residual lesion was treated with fractionated radiotherapy in 28 fractions. In May 2024, prolactin rose to 46.29 ng/mL with recurrent amenorrhea and returned to approximately 23 ng/mL in June 2024 after bromocriptine was reinitiated. This case illustrates that prolactin should be measured early in unexplained secondary amenorrhea, that moderate hyperprolactinemia in a macroadenoma must be interpreted cautiously, and that serial prolactin measurement combined with imaging is required during long-term multidisciplinary follow-up.