Snapshot A 42-year-old man presents to the clinic with complaint of decreased libido for the past month. He finds that he has a new problem of difficulty obtaining and maintaining an erection during sexual activity with his partner. He does not recall any instance of trauma to the area. On physical examination, he is found to have significantly impaired peripheral vision bilaterally and the chest findings seen in the image. Introduction Overview a prolactinoma is a non-cancerous pituitary tumor that overproduces the hormone prolactin treatment is usually with medication to restore a normal prolactin level or surgical resection Epidemiology Incidence most common pituitary adenoma (40% of all pituitary adenomas) Demographics more common in women than men peak prevalence in women ages 25-34 years Location pituitary gland lateral parts of anterior pituitary are most common sites ETIOLOGY Pathophysiology prolactinomas arise from monoclonal expansion of pituitary lactotrophs results in excess synthesis and secretion of prolactin ↑ prolactin inhibits GnRH secretion, leading to ↓ LH and FSH secretion can cause hypopituitarism from mass effect Presentation Symptoms headache visual changes visual field deficits blurred vision ↓ visual acuity signs of hyperprolactinemia in women amenorrhea or oligomenorrhea infertility loss of libido galactorrhea signs of hyperprolactinemia in men loss of libido impotence erectile dysfunction Physical exam bilateral hemianopsia mass lesion disrupts visual pathways crossing in the optic chiasm galactorrhea gynecomastia Imaging MRI or CT scan of the pituitary hypothalamic area indications determine if a mass lesion is present Studies Serum prolactin levels measure on 1 or more occassions Serum pregnancy test rule out pregnancy as the cause of secondary amenorrhea in reproductive-aged females Serum TSH rule out the possibility of ↑ prolactin level secondary to an elevated TRH level Serum testosterone levels measure in men presenting with symptoms of hypogonadism Treatment Medical bromocriptine or cabergoline (dopamine agonists) indications first-line treatment dopamine suppresses prolactin secretion Surgical surgical resection indications patients who cannot tolerate or do not wish to take dopamine agonists patients who do not respond to medical treatment or show progression after an initial response to medical treatment Complications Cranial nerve palsies due to mass effect Infertility