MUC16 and neoplasm: To address possible non-ovarian origins of the tumor, an ultrasound-guided transvaginal tru-cut biopsy was performed at the end of the ultrasound examination, and a blood sample was taken for CEA (carcinoembryogenic antigen), CA 19-9 (carbohydrate antigen 19-9), CA 125 (cancer antigen 125), and CA 15-3 (cancer antigen 15-3) to narrow down possible primary origins.