Multiple Loss of Heterozygosity in a Case of Rare Ovarian Mixed Germ Cell Tumor - Case Report and Overview of Literature

Abstract Malignant germ cell tumors (GCTs) are characterized by pluripotency and exhibit diverse embryonic and extraembryonic structures. Approximately 10% of malignant GCTs are mixed germ cell tumors. The precise histogenic origins of GCTs remain elusive, mostly because of their rare occurrence. The aim of this study is to determine the histogenic origin of an extremely rare mixed germ cell tumor of the ovary consisting of embryonal carcinoma and non-gestational choriocarcinoma components using short tandem repeats genotyping by the quantitative-fluorescence PCR and capillary electrophoresis. The comparison of short tandem repeat profiles between the patient's blood DNA and microdissected tumor revealed a consistent loss of heterozygosity at multiple short tandem repeat loci, indicating a clonal origin for both embryonal carcinoma and non-gestational choriocarcinoma components suggesting a potential origin in abnormal meiotic processes. The presence of loss of heterozygosity in the vast majority of examined loci suggests an origin from aberrant meiosis, possibly due to errors in meiosis I or meiosis II. Due to the rarity of mixed germ cell tumors, it is difficult to assess the clinical significance of this exact histogenic origin. Further studies and meta-analyses of a larger cohort are next essential step to explore the clinical significance of GCT histogenic origins. This article aims to improve the understanding of the GCT etiology.