This 6 year old girl was found to have XX/XY mosaicism during a postnatal workup as a follow up to a triple screen which suggested trisomy 18. She had bilateral salpingo-oophorectomy performed as prophylaxis for a potential malignancy.
Case Discussion
Gonadoblastoma is a tumour of immature gonadal sex cord and germ cells, which is considered a precursor lesion of malignant germ cell neoplasia. It is almost always associated with intersex-associated gonadal abnormalities, for example when Y chromosome material is present within an ovary. Approximately 80% of patients are phenotypically female (45X/46XY, 46XX/46XY). It is typically bilateral in the setting of dysgenetic gonads. Gonadectomy is the treatment of choice with excellent prognosis.
The sections demonstrate a mix of male and female gonadal structures (seminiferous tubule formation, epididymis and fallopian tube). There is ovarian cortex-type stroma and a few scattered gland-like structures. No primordial or primary follicles are present. The seminiferous tubule-like structures contain a small amount of Leydig cells and are lined by Sertoli cells (inhibin positive) with some immature germ cells (Oct3/4 positive). There are some well-defined, basement-membrane lined, round nests of large, pale seminoma-like cells admixed with small dark, angular, sex cord cells. Oct3/4 stains most of the germ cells.
This slide shows Oct3/4 stain. See Related Content for H&E and inhibin stains.
Mrkonjic, M., Chami, R. Ovary, Gonadoblastoma, Oct3/4 stain. Digital Laboratory Medicine Library, Dept of Laboratory Medicine & Pathobiology, University of Toronto. Published
. Accessed December 17, 2025. https://dev.dlml.cflabs.ca/image/ovary-gonadoblastoma-oct34-stain-lmp18234
