Abstract
Gliomatosis peritonei (GP) is a rare condition characterised by mature glial nodules that implant in the peritoneum, lymph nodes, or omentum. GP is typically associated with mature or immature ovarian teratomas and usually affects adolescent females. Although neuroglia may be a standard feature of mature ovarian teratomas, widespread peritoneal glial nodules, ascites, and pleural effusion are rare, particularly in the paediatric population. We report a case of a giant left mature ovarian teratoma associated with GP and omental splenunculus in a 12-year-old female who presented with constipation, an adnexal mass, ascites, pleural effusion, and elevated CA-125 levels. The patient successfully underwent fertility-sparing surgery in the form of a left salpingo-oophorectomy, omentectomy, and resection of peritoneal glial deposits. In light of the current scarcity of data on this clinical entity in the literature, we hope to raise awareness of this rare presentation of mature ovarian teratoma, the challenges associated with preoperative diagnosis, and the impact of fertility-sparing surgery on potential oncological and reproductive outcomes in a paediatric patient.