An adenoma is a benign tumor (-oma) of glandular origin. Adenomas can grow from many organs including the colon, adrenal glands, pituitary gland, thyroid, prostate, etc. Although these growths are benign, over time they may progress to become malignant, at which point they are called adenocarcinomas. Even while benign, they have the potential to cause serious health complications by compressing other structures (mass effect) and by producing large amounts of hormones in an unregulated, non-feedback-dependent manner (paraneoplastic syndrome).