Ovarian juvenile granulosa cell tumor: A report from the International Ovarian and Testicular Stromal Tumor and International Pleuropulmonary Blastoma/DICER1 Registries

Abstract Background Ovarian juvenile granulosa cell tumors (juvGCT) are rare sex cord‐stromal tumors that occur primarily in children and adolescents. This study summarizes the clinical presentation and outcomes of patients with juvGCT. Methods Patients were enrolled in the International Ovarian and Testicular Stromal Tumor and/or International Pleuropulmonary Blastoma/ DICER1 Registries. Available medical records were abstracted, and pathology was centrally reviewed. Surgical staging was classified using the 2014 International Federation of Gynecology and Obstetrics (FIGO) criteria. Results In total, 70 patients with juvGCT enrolled and were diagnosed between 2001 and 2024; most patients (81%, 57 of 70) presented with FIGO stage I disease. Adjuvant chemotherapy was given in 30% (21 of 70); all regimens were platinum‐based. Three‐year event‐free survival among patients with stage IA tumors was 80.2% (95% confidence interval [CI], 62.4%–100.0%), IC1 was 87.4 (95% CI, 72.4%–100.0%), IC2‐IC3 was 63.6% (95% CI, 40.7%–99.5%), and II‐IV was 48% (95% CI, 24.6%–93.8%). Of the patients with recurrent juvGCT with known mitotic index (MI), all had MI greater than 19 mitoses per 10 high power fields (HPF) at diagnosis. Conclusion Outcomes were worse for patients with FIGO stage ≥IC2 disease and for tumors with >19 mitoses per 10 HPF. Given the prognostic significance of MI, the authors strongly recommend the assessment of MI for all juvGCTs. More information about tumor biology is critical to identify which patients may benefit from adjuvant chemotherapy and to facilitate the development of novel therapies.