Aims: To determine how frequently endometrioid ovarian carcinomas (EOC) express WT1 protein, and to correlate the results with the presence of endometriosis and p53 immunoreactivity.
Methods: Forty-one grade 1-2 EOC were stained immunohistochemically for WT1 and p53 proteins. Twenty-one tumours were associated with endometriosis and 20 cases lacked such an association. WT1 expression in the tumour cell nuclei and/or cytoplasm was recorded. Nuclear p53 staining was assessed as diffuse (>50% cells positive), focal, or negative.
Results: Four of the 20 (20%) tumours in the endometriosis negative group showed nuclear WT1 staining, while none of the endometriosis-associated EOC was positive (p < 0.05). Two of the immunoreactive cases exhibited sertoliform/sex cord-like patterns. Focal cytoplasmic WT1 labelling was present in seven EOC, three of which showed sertoliform, spindle cell or corded and hyaline patterns. There was no correlation between WT1 expression and p53 immunoreactivity.
Conclusions: Nuclear WT1 expression is present in a minority of EOC and this should be considered if immunohistochemistry is used as an adjunct in sub-typing ovarian carcinomas. The negative correlation of WT1 staining with endometriosis supports the possibility that some EOC, including unusual histological variants, arise from the ovarian surface epithelium. Further studies of EOC should document any association with endometriosis.