Giant Immature ovarian teratoma with rupture and peritoneal dissemination mimicking carcinomatosis: Case report and brief literature review

Ovarian immature teratoma (IT) is a rare malignant germ cell tumor (GCT) that predominantly affects adolescents and young women and may present with rapid growth, rupture, and peritoneal dissemination, closely mimicking carcinomatosis. We report an 18-year-old nulligravid female who presented with a three-month history of progressive abdominal distension, pelvic pain, early satiety, weight loss, and dyspnea on exertion. Examination revealed a large abdominopelvic mass extending to the xiphoid process. Serum alpha-fetoprotein was markedly elevated (450 ng/mL), while beta-human chorionic gonadotropin (β-hCG) was normal. Contrast-enhanced CT demonstrated a large right adnexal solid-cystic mass with fat and calcifications, extensive peritoneal nodularity, omental caking, and hepatic surface implants. 
The patient underwent fertility-sparing right salpingo-oophorectomy with comprehensive staging; intraoperative tumor rupture occurred, likely related to rapid tumor growth and compromised vascular supply. Histopathology confirmed a FIGO stage IIIC, grade 3 immature teratoma with immature neuroepithelium showing GFAP and Oct4 positivity and a high proliferative index (Ki-67 approximately 70%). 
Following four cycles of bleomycin, etoposide, and cisplatin, complete remission with normalization of AFP was achieved. Recurrences involving the liver and peritoneum occurred at 28 months, necessitating secondary cytoreduction and second-line chemotherapy, after which the disease remained stable until loss to follow-up at 34 months. This case highlights the diagnostic challenges posed by ruptured giant immature teratomas, supports the feasibility of fertility-sparing management with BEP chemotherapy, and underscores the importance of long-term surveillance due to the risk of late recurrence.