Prolactin-Secreting Pituitary Adenomas: Pathology, Clinical Manifestations, and Diagnosis

Hyperprolactinemia is an important cause of hypogonadism in both genders, prolactinoma being its most common pathological cause. The pathophysiology of prolactinomas encompasses several mechanisms involving oncogenes, tumor suppressor genes, and growth factors. Clinical manifestations include menstrual disturbances, galactorrhea, sexual dysfunction, and infertility. Hyperprolactinemia also can be due to physiological (pregnancy and lactation), pharmacological (especially antipsychotics and gastrointestinal medications), and pathological causes as systemic diseases (renal and hepatic failure), endocrine diseases (hypothyroidism, Cushing disease), other pituitary or sellar region tumors causing pituitary stalk disconnection, and conditions leading to intercostal nerve stimulation as thoracic surgery and herpes zoster. Once the abovementioned causes are ruled out, the diagnosis of prolactinoma should be performed by laboratory and image (MRI) evaluation. Usually, serum prolactin levels parallel the tumor size. Laboratory and image pitfalls as macroprolactinemia, hook effect, and pituitary incidentaloma should be considered. Therefore, identifying the correct cause of hyperprolactinemia is crucial for the proper treatment.