We describe the clinical, radiological and pathological features of 5 cases of cystadenoma, one associated with cystadenocarcinoma. In 3 of these patients, the presence of thick wall, endoluminal buds and septations at imaging investigations was suggestive of the diagnosis of cystadenoma or cystadenocarcinoma. In 2 of these patients, these imaging features were lacking. In 2 of these patients, partial surgical resection was performed and was followed by recurrence of the tumor. In all cases, the diagnosis was confirmed by pathology examination of the resection specimen. In conclusion, this study shows that diagnosis of cystadenoma or cystadenocarcinoma may be very difficult because of the absence of suggestive imaging features in some cases, and confirms that complete resection of the tumor, allowing pathology confirmation, is needed for the optimal treatment of cystadenoma or cystadenocarcinoma.