Cystadenocarcinoma is a malignant form of a cystadenoma and is a malignant neoplasm derived from glandular epithelium, in which cystic accumulations of retained secretions are formed. The neoplastic cells manifest varying degrees of anaplasia and invasiveness, and local extension and metastases occur. Cystadenocarcinomas develop frequently in the ovaries, where pseudomucinous and serous types are recognized. Similar tumor histology has also been reported in the pancreas, although it is a considerably rarer entity.
It is the most common malignant ovarian tumor. Contains complex multi-loculated cyst but with exuberant solid areas in places. It usually presents with omental metastases which cause ascites.