Aggressive prolactinomas in men are associated with visual disturbances and pituitary hormone deficiencies.

Prolactinomas/lactotroph pituitary neuroendocrine tumors are ten times less frequent in men than in women and their characteristics are less well known. The latest WHO classification includes them among pituitary tumors with a high risk of recurrence. This study aimed to identify clinical parameters suggesting aggressive prolactinomas. We conducted a retrospective study in three hospitals in Galicia, Spain, including 41 men with prolactinomas. The mean age at diagnosis was 46.5 ± 16.2 years. Baseline prolactin levels were a median of 800 ng/ml, with 95% being macroprolactinomas. Aggressive prolactinomas (n = 10) compared to non-aggressive (n = 31), had higher rates of visual disturbances (60% vs. 13%; p = 0.005) and deficiencies of thyroid-stimulating hormone (70% vs. 13%; p = 0.001) and adrenocorticotropic hormone (50% vs. 7%; p = 0.006) at diagnosis. Prolactin levels correlated with tumor maximum diameter, more stronger in aggressive cases (r = 0.68; p = 0.047). In our study, a 24% of the prolactinomas were classified as aggressive. We found that prolactinomas in males presented with significantly elevated prolactin levels that correlate strongly with tumor diameter, as well as, visual disturbances and deficiencies of thyroid-stimulating hormone and adrenocorticotropic hormone, should raise suspicion of aggressive lactotroph pituitary neuroendocrine tumors/prolactinomas.