Intestinal differentiation in ovarian mucinous tumours.

Fifty-five ovarian mucinous tumours, 22 benign, 16 borderline and 17 malignant, were examined for intestinal differentiation (ID). This was defined by the presence of one or more of endocrine, absorptive, goblet or Paneth cells, and identified by routine haematoxylin and eosin as well as histochemical and immunoperoxidase techniques. Twenty benign (91%), 14 borderline (88%) and all malignant tumours contained foci of ID. The frequency of ID was not significantly different between the mucinous tumour types (chi-squared test for independence). Follow-up was available on all patients with borderline tumours: 14 were stage Ia, including both cases without ID, and 2 were stage Ic at presentation. All are alive and free of disease at 9-39 months (median 15.5 months). We conclude that the presence of ID in borderline mucinous tumours is unlikely to be of prognostic significance, and that a subdivision of these tumours into müllerian and intestinal types is unnecessary.