Prolactinomas in Men

Abstract

Prolactinomas in men have several peculiar features that distinguish them from female PRL-secreting tumors. They occur less frequently in the male gender but are usually larger, more frequently invasive, and more often aggressive than in women. Significantly higher prolactin concentrations are also observed in men as compared to women, especially in the case of macroprolactinoma. Sex differences in tumor behavior largely explain such characteristics, rather than the longer delay in making the diagnosis in men. The reasons for a more aggressive course of prolactinomas in men remain poorly understood, and some hypotheses will be discussed in this chapter. Striking differences also exist in the clinical presentation of prolactinoma. Most women will present with oligomenorrhea, infertility, and/or galactorrhea, while more than half of men initially complain from symptoms of mass effects. Male hypogonadism is often present but neglected, and the male reproductive axis appears to be less sensitive to hyperprolactinemia than the female one. Nonetheless, diagnosis of prolactinoma in men should rely on the same criteria as in women, and a similar therapeutic strategy should be used. Medical management with dopamine agonists (DA) is effective and should always be considered as the first-line therapy, also in men bearing very large and compressive tumors. Transsphenoidal surgery is indicated in patients who are either intolerant or resistant to dopamine agonists or who elect to undergo potential curative surgery. However, most male patients with a macroprolactinoma will require medical treatment to control prolactin hypersecretion after surgery.