Hyperprolactinemia caused by extra-pituitary prolactin secretion: a systematic review.

This study aims to summarize the clinical and pathological characteristics, as well as the treatment and therapeutic outcomes, of hyperprolactinemia caused by ectopic prolactin secretion. Case reports of patients with hyperprolactinemia caused by extra-pituitary prolactin secretion were collected by conducting searches in three databases using the terms (ectopic prolactin secretion) OR (ectopic hyperprolactinemia) OR (ectopic prolactinoma). Fifty-two cases were included (age: 45.5 years (34-55.25), baseline serum prolactin level: 218 ng/mL (110.3-680.5)). Extra-pituitary prolactin-secreting sites include ectopic pituitary adenomas (age: 55 years (47-65), baseline prolactin level: 382 ng/mL (200-1,598)) and non-pituitary-derived extracranial lesions (age: 38 years (30-45.5), baseline prolactin level: 148 ng/mL (75.25-246)). The most common symptoms of the two types of patients are, respectively, intracranial mass effect and galactorrhea or amenorrhea. 42.3% of cases received dopamine agonists as initial treatment, and among them, all patients with non-pituitary-derived lesions failed to achieve normalization in prolactin levels by receiving medication alone. 38.5% of cases received surgery as initial treatment, and 70% achieved an immediate decrease in prolactin level. In conclusion, hyperprolactinemia caused by ectopic prolactin secretion is rare, but it should still be considered in patients with hyperprolactinemia of unclear cause. Age, baseline prolactin levels, major symptoms, histology, pathology, and therapeutic outcomes varied between patients with prolactin-secreting ectopic pituitary adenomas and non-pituitary-derived lesions. Hyperprolactinemia caused by the latter had a female predominance. Dopamine agonists were effective for most ectopic pituitary adenomas, while patients with non-pituitary-derived lesions tended to resist dopamine agonists and responded well to surgery.