Gestational choriocarcinoma of the ovary diagnosed by analysis of tumour DNA

Gestational choriocarcinoma of the ovary is a rare form of malignancy which can be difficult to distinguish from primary ovarian choriocarcinoma. The ability to make such a diagnosis could, however, have important implications for therapy. We report here a case of choriocarcinoma whose origins were difficult to determine and which behaved clinically more like a primary rather than a gestational choriocarcinoma. We have analysed DNA from this tumour by using polymerase chain reaction (PCR) amplification of a range of polymorphic alleles and have demonstrated that the tumour was in fact gestational. Furthermore, the lack of chromosome Y sequences and the presence of heterozygosity of the spouse's alleles, indicated that this tumour arose as a result of dispermic fertilisation of an empty ovum by sperm carrying the X chromosome.