About 1% of childhood tumors can be malignant ovarian tumors and differential diagnosis with benign ones is sometimes difficult before surgery. Concerning the management of such tumors in adolescents for which future fertility is a concern, there is specific interest in their malignant potential and the possible use of ovarian-sparing operative techniques, as well the suitability of chemotherapy. To exemplify the difficulties of preoperative differential diagnosis, personalized approach and the difficulties of deciding to preserve the affected ovary, we report a rare case of a 14-year-old female adolescent with a growing abdominal painless mass and without any other chronic diseases. After physical examination and imaging investigations, laparoscopic surgical procedure is performed, the peritoneal cavity is explored and the well-delimited gigantic tumor is removed. Considering the normally looking pelvis and absence of adenopathy, as well as the patient's age and wish to have children, both ovaries are preserved. Laparoscopy has become the gold standard in the management of this condition, although there are few studies that report this approach in children; the differential diagnosis between a benign and a malignant tumor cannot be established exactly until after the histological examination, which revealed in our case a cystic teratoma with mature tissues. A better understanding of clinical features and evolution of giant ovarian masses in adolescents could help clinicians better diagnose and treat such lesions.