Common epithelial tumors of borderline malignancy (carcinomas of low malignant potential).

The creation of the category of ovarian borderline tumors has been a step forward in classification because it has segregated from the general group of common epithelial cancers a subgroup with an unusually good prognosis. Of all borderline tumors, the serous variety is the least difficult for the pathologist to diagnose. The mucinous borderline tumor is not as easy to recognize when an absence of invasion is used as the sole diagnostic criterion, but evaluation of other architectural as well as cytological features is helpful in making the diagnosis. Although the treatment of the majority of serous and mucinous borderline tumors is well standardized, therapy of residual serous borderline tumor is highly controversial and the treatment for pseudomyxoma peritonei, unsatisfactory. Borderline tumors exist in the endometrioid, clear cell, Brenner, and mixed common epithelial categories, but these tumors have been too rare to date in order to clearly characterize their clinical and pathological features. It is hoped that more can be learned about this general group of tumors by a more widespread recognition of their distinctive clinico-pathologic features and by their acceptance as a special subgroup of ovarian cancer. Their behavior differs strikingly from that of other types of malignant ovarian tumors and it is clear that their management should differ accordingly.