Beyond growing teratoma syndrome: post-treatment manifestations and diagnostic challenges following ovarian immature teratoma.

Growing teratoma syndrome (GTS) is a rare condition classically associated with platinum-based chemotherapy for malignant ovarian germ cell tumors. However, post-treatment findings following ovarian immature teratoma may represent a broader spectrum of entities that mimic recurrent malignancy and create substantial diagnostic challenges. Given the rarity of these conditions and their diverse clinical presentations, we present two illustrative cases managed at the Department of Gynecology and Gynecologic Oncology, University Hospital in Cracow, and review of the available literature. The first case involved a patient with ovarian immature teratoma who developed a classical post-chemotherapy GTS requiring surgical resection. During follow-up, a subsequent suspicious lesion demonstrated increased metabolic activity on positron emission tomography and was associated with mildly elevated tumor markers, raising concern for recurrent disease. Histopathological examination ultimately revealed a foreign-body granulomatous reaction. The second case involved a patient treated surgically for ovarian immature teratoma without adjuvant chemotherapy who subsequently developed peritoneal gliomatosis coexisting with deep infiltrating endometriosis, initially raising suspicion of intraperitoneal dissemination. These cases highlight the broad spectrum of post-treatment manifestations that may occur following ovarian immature teratoma. Enlarging masses, peritoneal implants, metabolically active lesions, and elevated tumor markers do not necessarily indicate malignant recurrence. Accurate diagnosis frequently requires correlation of imaging findings with surgical and histopathological assessment, and awareness of these rare entities is essential for appropriate management and surveillance.