Mixed germ cell tumours of the ovary are rare malignant neoplasms containing combinations of two or more types of germ cell elements. The aim of the study was to review biopsy examinations, medical records, treatment strategy, follow-up and outcome of all girls treated for mixed germ cell tumour of the ovary at the Department of Pediatric Oncology, University Hospital Motol during the period 1979–2002. Archival slides of all tumours were reviewed and tumours were classified according to the WHO system. The clinical data on surgical treatment, chemotherapy and radiotherapy used and followup information were obtained in all girls. The staging was reviewed retrospectively on the basis of surgical and pathological findings and results of imaging investigations, and it was outlined according to the most recent FIGO criteria and TNM classification. Sixteen girls with mixed germ cell tumour of the ovary, age range 3 years 11 months to 17 years 8 months (median 12 years) were treated. All girls presented with unilateral tumour of the ovary and all underwent surgery as an initial treatment. The most common presenting symptom was abdominal pain, occurring in ten patients. The original diagnosis of mixed histology was confirmed in all cases; in five cases the tumour contained three histologic components, in eleven cases the tumour consisted of two germ cell types. All tumours contained elements of yolk sac tumour, followed by immature teratoma, embryonal carcinoma, dysgerminoma and mature teratoma. At the time of diagnosis three patients had stage I disease, four patients stage II, seven stage III and two stage IV disease. All patients were treated with chemotherapy after surgery, predominantly with platinum-based regimens (PVB, BEP). Three patients treated initially with MAC (metothrexate, dactinomycin, cyclophosphamide) were diagnosed in the early eighties. In seven girls with advanced disease treated in the early years, radiotherapy was administered to the pelvis or whole abdomen. Overall survival and event-free survival were 80% and 81.3% respectively (median follow- up time 7.6 years). Three patients have died from the disease, two progressed on treatment (MAC), one girl relapsed three months after finishing therapy, no further therapy was administered. One girl underwent resection of tumour of her remaining ovary 24 months after original diagnosis. Histology showed mixed serous and mucinous cystadenoma. The latest examinations revealed that all other patients were in good health. Microscopic examination should be extensive and careful to find out all types of malignant germ cell elements. Platinum based chemotherapy is effective in the management of children and adolescents with mixed germ cell tumors of the ovary. Chemosensitivity of these tumours a most girls to have conservative surgery with possible preservation of reproductive function.

        Key words: mixed germ cell tumour – ovary – childhood – adolescence – treatment – chemotherapy