The incidence (rate per 100 000) of borderline ovarian tumors (BOTs) increases progressively with age, starting at 15-19 years and peaking at around 4.5 cases per 100 000 at an age of 55-59 years (LE3) with a median age of 46 years. The five year survival for FIGO stages I, II, III and IV is 99.7 % (95 % CI: 96.2-100 %), 99.6 % (95 % CI: 92.6-100 %), 95.3 % (95 % CI: 91.8-97.4 %) and 77.1 % (95 % CI: 58.0-88.3 %), respectively (LE3). An epidemiological association exists between the individual risk of BOT and family history of BOT and certain other cancers (pancreatic, lung, bone, leukemia) (LE3), a personal history of benign ovarian cyst (LE2), a personal history of tubo-ovarian infection (LE3), the use of a levonorgestrel intrauterine device (LE3), oral contraceptive use (LE3), multiparity (LE3), Hormonal replacement therapy (LE3), high consumption of Coumestrol (LE4), medical treatment for infertility with progesterone (LE3) and non-steroidal anti-inflammatory drug use (LE3). Screening for BOTs is not recommended for patients (Grade C). The overall risk of recurrence of BOTs varies between 2% and 24 %, with an overall survival greater than 94 % at 10 years, and the risk of an invasive recurrence of a BOT ranges from 0.5 % to 3.8 %. The use of scores and nomograms can be useful in assessing the risk of recurrence, and providing patients with information (Grade C). The WHO classification is recommended for classifying BOTs. It is recommended that the presence of a microinvasive focus (<5 mm) and microinvasive carcinoma (<5 mm with an atypical nuclei and a desmoplastic stroma reaction) within a BOT be reported. In cases of serous BOT, it is recommended to specify the classic histological subtype or micropapillary / cribriform type (Grade C). When confronted with a BOT, it is recommended that the invasive or non-invasive nature of peritoneal implants can be investigated based solely on the invasion and destruction of underlying adipose or peritoneal tissue which has a desmoplastic stromal reaction where in contact with the invasive clusters (Grade B). For bilateral mucinous BOTs and / or in cases with peritoneal implants or peritoneal pseudomyxoma, it is recommended to also look for a primitive digestive or pancreato-biliary cancer (Grade C). It is recommended to sample ovarian tumors suspected of being BOTs by focusing samples on vegetations and solid components, with at least 1 sample per cm in tumors with a size less than 10 cm and 2 samples per cm in tumors with a size greater than 10 cm (Grade C). In cases of BOTs and in the absence of macroscopic omental involvement after careful macroscopic examination, it is recommended to perform at least 4-6 systematic sampling blocks and to include all peritoneal implants (Grade C). It is recommended to consult an expert pathologist in gynecology when a BOT suspicion requires intraoperative extemporaneous histology (grade C). Endo-vaginal and suprapubic ultrasonography are recommended for the analysis of an ovarian mass (Grade A). In case of an undetermined ovarian lesion on ultrasonography, it is recommended that a pelvic MRI be performed (Grade A). To analyze an adnexal mass with MRI, it is recommended to use an MRI protocol with T2, T1, T1 Fat Sat, dynamic and diffusion sequences as well as gadolinium injection (Grade B). To characterize an adnexal mass with MRI, it is recommended to include a score system for malignancy (ADNEX MR/O-RADS) (Grade C) in the report and to formulate a histological hypothesis (Grade C). Pelvic MRI is recommended to characterize a tumor suspected of being a BOT (Grade C). Macroscopic MRI features should be analyzed to differentiate BOT subtypes (Grade C). Pelvic ultrasound is the first-line examination for the detection and characterization of adnexal masses during pregnancy (Grade C). Pelvic MRI is recommended from 12 weeks of gestation in case of an indeterminate adnexal mass and should provide a diagnostic score (Grade C). Gadolinium injection must be minimized as fetal impairment has been proven (Grade C). It is recommended that serum levels of HE4 and CA125 be evaluated and that the ROMA score for the diagnosis of an indeterminate ovarian mass on imaging be used (grade A). In case of suspicion of a mucinous BOT on imaging, dosage of serum levels of CA 19-9 can be considered (Grade C). If the determination of tumor markers is normal preoperatively, routine dosage of tumor markers in BOT follow-up is not recommended (Grade C). In case of preoperative elevation in tumor markers, the determination of serum CA 125 levels is recommended in the follow-up of BOT (Grade B). When conservative treatment of a BOT has been adopted, the use of endovaginal and transabdominal ultrasonography is recommended during follow-up (Grade B).