An Uncommon Presentation of Growing Teratoma Syndrome in a Patient Treated for Testicular Immature Teratoma: A Case Report.

Growing teratoma syndrome (GTS) is an uncommon post-chemotherapy event in non-seminomatous germ cell tumors and presents as enlarging masses composed of mature teratoma despite normalized markers. As systemic therapy is generally ineffective, treatment focuses on surgical excision. We report the case of a 30-year-old male with an immature teratoma of the right testis who, after completing chemotherapy with normalized tumor markers, developed enlarging lymph node masses histologically confirmed as mature teratoma, consistent with GTS. This case highlights the importance of maintaining a high index of suspicion for GTS in patients with immature teratomas undergoing chemotherapy and underscores the critical role of multidisciplinary follow-up to ensure timely diagnosis and effective management.