Malignant ovarian germ cell tumours in gonadal Y chromosome mosaicism

Previous studies have shown that two partially overlapping mechanisms are responsible for the development of malignant ovarian germ cell tumours (MOGCT): either spontaneous mutations, mostly in KIT gene, or the presence of Y chromosome material, in dysgenetic gonads. While unilateral oophorectomy and preservation of fertility is favourable in most cases, presence of whole or part of Y chromosome in dysgenetic ovaries is associated with a risk of bilateral germ cell tumour development. The aim of this study was to evaluate the frequency of Y chromosome material in these tumours.

A total of 47 cases with histopathologic diagnosis of malignant germ cell tumour were selected in a period of 9 years. A relative quantitative PCR (RQ-PCR) method was designed and validated to detect testis-specific protein Y-encoded (TSPY) gene on Y chromosome. After DNA extraction, TSPY gene was sought as a surrogate of Y chromosome.

Significant amounts of TSPY gene were found in seven cases, two of which had gonadoblastoma and one had cytogenetic proof of Y chromosome presence.

Some MOGCTs develop on the background of gonadal mosaicism and gonadal dysgenesis. Bilateral oophorectomy may be indicated in patients with these disorders because they are at risk of developing an MOGCT on the contralateral gonad. Moreover, this chromosomal abnormality is hardly found by routine methods, and the abnormality is more easily sought in MOGCT cells by means of RQ-PCR.