A benign or borderline cystic epithelial neoplasm arising from the glandular epithelium. The epithelial cells line the cystic spaces which contain serous or mucinous fluid. Representative examples include ovarian and pancreatic cystadenomas. The disease is cystadenoma (Monarch Disease Ontology id MONDO_0002369). Also known as: cystadenoma (morphologic abnormality), cystadenoma, benign, cystoma.