Patients with ovarian endometriosis (OE) are known to have a 2.5-fold increase in the risk of malignant neoplasms. OE is polymorphic condition histologically subdivided on two forms: “without atypia” and “with atypia”. First form is considered benign, while second one is precursor of ovarian malignant transformation.

Assess of the morphological and immunohistochemical characteristics indicative of the risk of malignant neoplastic transformation of OE atypical lesions.

Seventy-eight fragments of ovarian tissue (resected regarding ovarian endometrioid cists) were studied histologically for determination of cystic ovarian endometriosis foci with and without atypia. Thirty-five histological slides with OE and 8 slides with adenocarcinomas of different types were studied immunohistochemically. Monoclonal antibodies to Ki-67, Всl-2, р53 proteins and polyclonal antibodies to HNF-1β were used. Results were evaluated by means of Histological score (H-score) method.

Thirty-five foci of cystic OE without atypia and 32 foci with epithelial atypia were observed. In foci with epithelial atypia, the expression of Ki-67, Bcl-2 and HNF-1β was significantly higher relatively to the foci without atypia, while expression of р53 was the same in foci with and without atypia. From 4 subtypes of studied ovarian adenocarcinomas the expression of HNF-1β was only observed in clear cell adenocarcinoma.

Enhanced expression of biomarkers Ki-67, Bcl-2 and HNF-1β in cystic OE with atypia indicates on the risk of malignant transformation of lesions with atypia. Using of these biomarkers can be useful for differential diagnostics of OE with and without atypia and for decision about surgical treatment.