Answer: an adenoma
Explanation: An adenoma is a benign tumor that arises from the epithelial cells of a gland or gland-like structure. It is typically composed of glandular tissue, although it may contain some connective tissue. Adenomas can occur in any organ or tissue that contains glandular tissue, such as the thyroid, pituitary, adrenal, pancreas, prostate, and ovaries. They are usually slow-growing and may remain asymptomatic for long periods of time.