Giant serous cystadenoma masquerading as ascites in an adolescent: a case report

Giant ovarian serous cystadenomas are rare in adolescents and may mimic ascites, leading to diagnostic delays. Imaging and laboratory evaluation are essential for early treatment and fertility preservation. A 16-year-old Igbo girl from southeastern Nigeria presented with progressive abdominal distension, pain, persistent vaginal bleeding, and anemia. Initial ultrasound suggested free peritoneal fluid (ascites), but extended field of view (EFOV) imaging revealed a large cystic mass occupying most of the abdomen. Laboratory tests confirmed iron deficiency anemia and hormonal imbalance. Surgical exploration identified a 4.25 kg serous cystadenoma arising from the right ovary. Histopathology confirmed a benign epithelial origin. Giant serous cystadenomas, though uncommon in adolescence, should be considered in cases of unexplained abdominal enlargement. EFOV ultrasound, combined with laboratory workup and histology, is effective for distinguishing cystic masses from ascites. Diagnostic vigilance and ultrasound skill are crucial for accurate diagnosis and optimal outcomes in resource limited settings.