Mucinous borderline tumors (MBT) - endocervical type: They show complex papillary architecture similar to serous borderline tumors. The papillae are lined by mucinous cells resembling endocervical epithelium as well as polygonal cells with abundant eosinophilic cytoplasm. Additional cell types that may be seen include ciliated serous cells, endometrioid cells, and squamous epithelium. Most cases show neutrophilic infiltrate in the stroma and the neoplastic epithelium of the papillae as well as within intraluminal mucin. Mild to moderate nuclear atypia may be present. Mitotic activity is not increased. There is no destructive stromal invasion.