A report describes a case of a 14-year-old girl with ovarian mucinous adenocarcinoma who complained of lower abdominal pain for around 3 weeks and presented with a doubt of an 8 cm left ovarian cyst as revealed by a USG scan. Her period was regular since menarche at the age of 12 and was earlier diagnosed with albinism. No abnormality was detected on physical examination, while the ultrasound scan examination of the pelvis showed a cystic mass of 7 x 5.5 cm in the left ovary. MRI images of the abdomen and pelvis too confirmed the USG finding by displaying left ovarian mass with solid and cystic components of 5 x 5 x 7 cm dimension. Preoperative serum levels according to the ROMA test showed elevation of CA-125: 125.7 IU/mL (normal: < 35 IU/mL) and normal HE4: 36 pmol/L (normal: < 70 pmoI/L). a-fetoprotein (a-FP) was 2.68 ng/mL (normal: 0.79–4.69 ng/mL) and human chorionic gonadotropin (HCG) was < 0.5 mlU/mL. Considering the age of the patients and to avoid invasiveness, laparoscopic surgery was planned.Laparoscopic surgery with the resection of the tumor, left salpingo-oophorectomy and biopsy from the right ovary, was accomplished in oncological purity. Final histology analysis revealed adenocarcinoma of intestinal type of the left ovary without fallopian tube infiltration, but with simple carcinoma cells in peritoneal fluid. No oncological changes were seen in the specimen taken from the right ovary. Following histopathological reports, the Oncological Council conducted urgent gastroenterological consultation, gastroscopy, colonoscopy and a PET scan, which all did not show any abnormalities. The results of diagnostic tests prompted the IIB stage of disease according to FIGO 2014. The decision of the European Reference Network for Pediatric Oncology directed six cycles of chemotherapy with an application of carboplatin and paclitaxel. Six months after completing the treatment process, all tumor markers came out to be negative, the control MRI scan was correct and an ultrasonography examination of the pelvis and abdominal was free of any abnormalities. A further follow-up of the patient was recommended.SOURCE- Drosdzol-Cop A, Mizia-Malarz A, Wilk K, Koszutski T, Wilk K, Stojko F. Ovarian adenocarcinoma in 14-year-old girl. Ginekologia Polska 2022;93(4): 343–344. DOI 10.5603/GP.a2022.0026