Case Report: Intracranial growing teratoma syndrome in two children with suprasellar mixed germ cell tumors: implications for the timing of surgery.

Background: Intracranial growing teratoma syndrome (iGTS) is characterized by paradoxical tumor enlargement despite normalization of tumor markers during treatment of germ cell tumors. Its recognition is critical, particularly in the suprasellar region where mass effect can lead to significant morbidity. Case presentation: We report two pediatric patients with suprasellar mixed germ cell tumors treated with alternating etoposide-cisplatin and ifosfamide-etoposide chemotherapy. In both cases, serum alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (β-HCG) levels declined markedly during treatment; however, clinical deterioration and radiologic tumor enlargement occurred. Surgical resection revealed mature teratoma in both cases, confirming classic iGTS after histopathologic review. Gross total resection was achieved in both cases, followed by completion of chemotherapy and craniospinal irradiation. At follow-up, both patients remained in remission but developed permanent hypothalamic-pituitary dysfunction. Results: These cases illustrate a clear dissociation between biochemical response and local mass enlargement, consistent with classic iGTS in both patients. Conclusion: Declining tumor markers should not be interpreted as reassurance in the presence of worsening symptoms or tumor enlargement. Early surgical intervention should be considered in selected patients to relieve mass effect and potentially reduce long-term morbidity.