Peritoneal epithelial lesions associated with proliferative serous tumours of ovary.

The peritoneal epithelial lesions in 40 cases of proliferating ovarian serous tumour are described. The lesions were varied and of both neoplastic and non-neoplastic form. The most common was serous tumour similar to that in the associated ovarian neoplasm. Tumour of this type was present in some or all of the peritoneal lesions in 77.5% of cases. In nearly two-thirds, the tumour was superficial; in the rest it invaded omentum. Occasionally, the infiltrating tumour was poorly differentiated. Benign tubular lesions resembling endosalpingiosis occurred in 16 (40%) of the 40 cases, but in seven it was associated with serous tumour. Psammoma bodies frequently accompanied serous tumour and endosalpingiosis and in occasional cases the majority of lesions consisted of psammomatous foci. The duration of follow up is too short to adequately assess the biological significance of these findings but it is clear that the peritoneal tumour occasionally may kill the patient within a few years. 'Serous tumour of low malignant potential' is the most appropriate term to describe the general group of ovarian serous tumours of so-called 'borderline malignant' type.