EP34.38: Decidualised endometrioma during pregnancy: a cyst classified as malignant according the IOTA simple rules

We present the case of a 38-year-old woman, nulliparous, who was referred to our centre to perform an infertility study. In the first transvaginal ultrasound, we visualised a unilocular cyst in the left ovary of 30 x 41 x 36 mm with irregular wall and slightly hyperechogenic (score colour 1). Ecogenicity of cyst fluid: mixed. The first ultrasound diagnosis was a probably atypical endometrioma and a new ultrasound control was requested in 3 months. The patient underwent in vitro fertilisation in an external centre, so she came to control 5 months later, 13+6 weeks pregnant. Ultrasound showed sonographic changes in the cyst. On this occasion, the same explorer described it as unilocular-solid cyst of 26 x 29 x 36 mm, anechoic, with multiple papillary projections (>4) that were highly vascularised on Doppler examination. According to the IOTA simple rules, it was classified as probably malignant. The case was discussed and, finally, a laparoscopic left adnexectomy with intraoperative anatomopathological study was proposed to the patient. Surgery was performed when the patient was 15+5 weeks pregnant, and the histological examination of the surgical piece showed an endometriotic cyst with extensive decidual changes of the stroma and the cyst wall. According to available literature, it is evident that decidualised endometriomas with papillary projections can cause important diagnostic difficulties, especially in women without ultrasound diagnosis of endometrioma prior to gestation, because they tend to present as a complex adnexal cystic mass, which can mimic ovarian malignancy. However, and according to published evidence, it seems reasonable to suggest expectant management of cysts with papillary projections detected during pregnancy only in patients who have an ultrasound diagnosis prior to pregnancy of an endometrioma in the same ovary. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.