Mucinous borderline tumors (MBT) - endocervical type account for approximately 15% of MBT. They are seen in somewhat younger age-group than intestinal type and often associated with endometriosis. They are more likely to be bilateral and present at advanced stages. They are frequently unilocular (80% cases) or contain fewer than 3 locules in contrast to the intestinal type which are usually multilocular. They show papillary architecture with atypical cells lining stromal papillae.