A 30 year-old nulliparous woman, was referred to our center during her active surveillance program for previous serous borderline ovarian tumor (BOT). She underwent right salpingo-oophorectomy and then left ovarian cystectomy for primary and recurrent BOT in 2015 and 2016, respectively. At ultrasound examination, an unilocular-solid lesion of 16x12x16 mm in size was detected in the left ovary and it appeared as a mass with anechoic echogenicity, irregular contours, and presence of a papillary projection of 11x10x11 mm in size (Fig. 1 a and b). This article is protected by copyright. All rights reserved.