Case presentation An 11-year-old girl presented with left lower quadrant abdominal pain, which was colicky and progressively worsened over the past seven months. The pain radiated to her back and was aggravated by her menstrual cycle.

Gynecological evaluation – Left lower abdominal swelling and tenderness Laboratory results Hemoglobin – 13.6 g/dL WBC – 6,600/mL Beta-human chorionic gonadotropin and cancer antigen 125 – Normal Pelvic ultrasound (Cover image C) Large left ovarian lesion (9 x 7 cm) with thickened walls Complex left ovarian cyst Pelvic MRI Giant multiloculated left ovarian mass (Cover image A) Complex multilocular lesion (13 x 8 cm) covering the left ovary with a thick wall (Cover image B) Treatment and histopathological examination A left oophorectomy was performed Specimen had a large gelatinous mass (14 x 8 cm; Figure 1) Β  Figure 1 . Histopathological examination of left…