CLAUDIA MEHEDINTU, MARINA ANTONOVICI, LACRAMIOARA BRINDUSE, ELVIRA BRATILA, RUXANDRA STANCULESCU, COSTIN BERCEANU, OVIDIU BRATU1, SILVIU PITURU, MIRCEA ONOFRIESCU, DANIELA ROXANA MATASARIU THE INFLUENCE OF PROGESTERONE ON IMMUNOHYSTOCHEMICAL MARKERS IN ENDOMETRIOSIS Endometriosis, one of the most common gynecologic pathologies, is defined as an inflammatory, estrogen-dependent disease characterized by the growth of endometrial stroma and glands outside the uterine cavity. It is a multifactorial disease, conditioned by genetic and immune factors and triggered by hormonal and environmental factors. Estrogen receptors (ER) and progesterone receptors (PR) expression is significantly modified in endometriotic tissue, compared to normal endometrium. We performed a prospective study that included 16 patients with endometriosis: 9 patients that underwent progesterone treatment with 0.075 mg desogestrel, daily for 24 weeks prior to the surgical procedure, and 7 patients that did not follow any kind of treatment. The purpose of the study was to evaluate the changes that occurred in the expression of ER, PR, B-cell lymphoma 2 (Bcl-2) and Ki-67 from the endometriotic tissue. Oral 0.075 mg desogestrel administration proved its benefits in the management of endometriomas.