Mucinous adenocarcinoma arising from a mature cystic teratoma of the ovary in a pediatric patient: A rare case report.

Mature cystic teratomas (MCTs) are common ovarian neoplasms that rarely undergo malignant transformation, particularly in pediatric patients. We report a rare case of a 5-year-old girl presenting with abdominal distension and back pain, initially managed with incomplete excision of an ovarian mass without histopathological evaluation. Recurrence led to debulking surgery revealing a mixed germ cell tumor, and subsequent imaging identified a residual abdominopelvic mass with elevated alpha-fetoprotein levels. Magnetic resonance imaging (MRI) findings demonstrated a solid-cystic tumor with hemorrhagic components. Complete surgical resection was performed, and histopathology confirmed mucinous adenocarcinoma arising from an MCT. Postoperative imaging showed no residual disease. This case underscores the importance of thorough histopathological analysis, multidisciplinary management, and long-term follow-up in addressing rare and aggressive ovarian tumors in pediatric patients.