Ovarian borderline tumours: a review with emphasis on controversial areas

Ovarian borderline tumours are relatively uncommon, but by no means rare, neoplasms. Most are of serous or mucinous type with other morphological variants being much more uncommon. This review discusses the pathological features and some clinical aspects of ovarian borderline tumours, concentrating on those of serous and mucinous type. Borderline endometrioid, Brenner and clear cell tumours are briefly discussed. Controversial and often poorly understood topics covered include the relationship between borderline tumours and carcinomas, the criteria for and significance of microinvasion, the significance of a micropapillary architecture in a serous borderline tumour, the diagnostic criteria for and significance of extraovarian “implants”, lymph node involvement, staging issues and tumour behaviour. Ovarian borderline tumours have an excellent prognosis, although a small percentage will recur or the patient will develop progressive disease. It has been suggested that the term borderline tumour be abandoned but it is argued that this terminology should be retained for both serous and mucinous neoplasms because of the risk of extraovarian disease in serous borderline tumours and the large size and heterogeneity of mucinous borderline tumours which may result in an invasive focus being undetected by the pathologist.