adenom

An adenoma is a benign tumor that arises from glandular epithelium and forms gland-like structures or tubules. Adenomas are typically well circumscribed and noninvasive, but they can cause symptoms by mass effect or, in some cases, by producing hormones. They must be distinguished from adenocarcinomas, which are malignant.

Adenomas can occur in many organs. Colorectal adenomas (adenomatous polyps) are among the most common and are considered precursor lesions to colorectal cancer. They are often found incidentally during screening and are classified by histology as tubular, tubulovillous, or villous; larger or high-grade adenomas carry a higher cancer risk. In the pituitary, adenomas arise from pituitary cells and can be hormonally active (for example, prolactin-secreting or growth hormone–secreting adenomas) or nonfunctioning. They may cause hormonal excess symptoms or mass effect, such as vision changes, and treatment may involve surgery, medications, or radiotherapy. Adrenal adenomas are cortical tumors that are usually nonfunctional and found incidentally; some secrete cortisol, aldosterone, or androgens, leading to endocrine syndromes and requiring targeted management. Hepatic adenomas are rare liver tumors associated with estrogen exposure in some cases; they can rupture and bleed, and management depends on size and symptoms. Thyroid and ovarian adenomas are other examples; many are noncancerous but may require evaluation to exclude malignancy or address symptoms.

Diagnosis typically involves imaging and histopathologic examination after biopsy or surgical removal. Prognosis is generally favorable after complete excision or spontaneous regression in some contexts; the key clinical consideration is distinguishing benign adenomas from malignant tumors and addressing any hormone-related effects when present.