Introduction/Background The aim of this study is to present a case of an ovarian endometrioma with atypia.

Methodology The present study is a case report and literature review.

Results A 43-year-old patient underwent laparoscopy for the excision of a cystic mass of the left ovary. Intraoperatively the mass was recognized as an endometrioma and other findings included multiple adhesions and a rectovaginal septum nodule. The endometrioma was excised and adhesiolysis was performed. The histology report was diagnostic of atypical endometriosis of the ovary, due to the presence of epithelial micropapillary tufts and extensive nuclear atypia.

Atypical endometriosis is characterized histologically as a lesion with features that fall between benign and malignant, such as nuclear enlargement and hyperchromatism, a high nuclear to cytoplasmic ratio, cellular crowding and stratification or tufting and the presence of atypical glands. It is observed in less than 1–3% of endometriomas and is considered to have a malignant potential to endometriosis - associated ovarian cancer, such as the endometrioid and clear cell subtypes. Literature is limited and inadequate in order to safely estimate the risk of malignant transition, the natural course or the best clinical management of atypical endometriosis.

Conclusion Atypical endometriosis may be considered as a precancerous lesion and requires close follow - up or prophylactic treatment.

Disclosure Nothing to disclose.