Introduction/Background Mesonephric-like adenocarcinom is a recently described tumor, included in the world health Organization (WHO) Classification in 2020. Clinical reports are scant, but worse prognosis has been reported.

Methodology We describe two clinical cases and review of the literature.

Results Histological features overlap with several more common gynecological tumors.

Immunohistochemical specific pattern includes PAX8+, GATA3+, CK7+, vimentin+, ER/PR-, WT1-, napsin A-, Inhibin-, P53 wild type.

We present two cases of Mesonepric-like ovarian adenocarcinoma in IA and IIIC stages, in which the diagnosis was suspected by their unusual staining pattern and confirmed by specific immunochemistry.

One of the tumors was associated with endometriosis e and the other one presented concomitant endometrioid adenocarcinoma of the ovary.

Conclusion Mesonephric-like adenocarcinoma of the ovary can be suspected in histological samples with atypical features (unusual pattern of spread, incongruent basic immunostaining,...). Diagnosis is made by histological features and specific immunostaining.

Disclosures We have no conflicts of interest to disclose.

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Abstract 924 Figure 1