A case report of a young girl with mucinous borderline tumor
Ovarian tumors are rare in children and adolescents. The incidence of malignancies in these groups is 1% to 1.5%, and the common histologic type is non-epithelial type such as germ cell tumors or sex cord-stromal tumors. Epithelial ovarian cancers are commonly observed in adults, and the mean age at diagnosis of ovarian cancer is 63 years. It is important to correctly diagnose these rare tumors in young women in order to assure proper treatment and to prevent mortality and preserve fertility. We present a case of a 13-year-old girl with a giant ovarian mucinous borderline tumor.

Case report
A 13-year-old girl who presented with painless abdominal distension over five months was referred to our institution for diagnosis and treatment in June 2015. She had no medical history with the exception of abdominal distension and amenorrhea. The last menstrual cycle was 10 months prior. Her menstrual cycle had been irregular since she experienced menarche at the age of 12 years. There was no reported use of oral contraceptives, and she was not known to be sexually active. Her physical examination showed abdominal distension and a firm mass without tenderness, extending from the pelvis to the umbilicus....