Pituitary Adenoma
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Overview
Plain-Language Overview
Pituitary adenoma is a noncancerous tumor that develops in the pituitary gland, a small organ at the base of the brain responsible for controlling many important hormones. This tumor can affect the body's hormone balance by producing too much or too little of certain hormones, leading to various symptoms. Common effects include changes in growth, metabolism, and reproductive function. Some people may experience headaches or vision problems if the tumor presses on nearby structures. The condition involves the endocrine system and can impact overall health by disrupting normal hormone regulation.
Clinical Definition
Pituitary adenoma is a benign neoplasm arising from the anterior pituitary gland cells, typically caused by monoclonal proliferation of hormone-secreting or nonfunctioning cells. These tumors are classified based on size into microadenomas (<10 mm) and macroadenomas (≥10 mm), and by hormone secretion status as functioning or nonfunctioning adenomas. Functioning adenomas secrete excess hormones such as prolactin, growth hormone, or ACTH, leading to clinical syndromes like prolactinoma, acromegaly, or Cushing disease. Nonfunctioning adenomas often present due to mass effect symptoms like visual field defects from optic chiasm compression. The major clinical significance lies in hormone dysregulation and potential local invasion causing neurological deficits.