A malignant cystic epithelial neoplasm arising from the glandular epithelium. The malignant epithelial cells invade the stroma. The cystic spaces contain serous or mucinous fluid. Representative examples include ovarian and pancreatic cystadenocarcinomas. The disease is MONDO_0005596 (cystadenocarcinoma). Also known as: cystadenocarcinoma (morphologic abnormality), cystadenocarcinoma NOS (morphologic abnormality), cystadenocarcinoma, malignant.