adenoma

a benign tumour of epithelial origin that is derived from glandular tissue or exhibits clearly defined glandular structures. Adenomas may undergo malignant change ( see ADENOCARCINOMA ). Some show recognizable tissue elements, such as fibrous tissue ( fibroadenomas), while others, such as some bronchial adenomas, may produce active compounds giving rise to clinical syndromes (see ARGENTAFFINOMA ). Tumours in certain organs, including the pituitary gland, are often classified by their histological staining affinities, for example eosinophil, basophil, and chromophobe adenomas.