Benign mucinous tumors are typically multilocular (have several lobes), and the cysts have a smooth lining of epithelium that resembles endocervical epithelial cells with small numbers of gastrointestinal-type epithelial cells.
Borderline and malignant mucinous tumors often have papillae and solid areas.
It is well documented that malignancy may be only focally present in mucinous neoplasms of the ovary, so thorough sampling is imperative.
The major distinguishing features of mucinous tumors are that the tumors are filled with a mucus-like material, which gives them their name; this mucus is produced by mucus-secreting goblet cells very similar to the cells lining normal intestine.
See article by Tworoger SS in Cancer March 1, 2008 using data from the Nurses Health Study.