What is the most common anterior pituitary gland tumor?

• A. Prolactinoma
• B. GH-secreting adenoma
• C. Corticotroph adenoma
• D. Thyrotroph adenoma

Answer: (A)

A prolactin-secreting adenoma (prolactinoma) is the most common tumor of the anterior pituitary. Prolactin—produced by lactotroph cells—accounts for the largest share of pituitary adenomas, and these tumors are frequently microadenomas that grow slowly. Clinically, they often present with symptoms related to excess prolactin, such as galactorrhea and menstrual disturbances in women, and reduced libido or hypogonadism in men. Because lactotrophs are the most common cell type that undergoes neoplastic change in the pituitary, prolactinomas outnumber GH-secreting, corticotroph, and thyrotroph adenomas. While other causes of elevated prolactin exist (medications, hypothyroidism, stalk effect), when a tumor is involved, prolactinomas are still the most frequent.