Eosinophilic Cells in Endometrial Carcinoma as a Predictor of BRAF Mutation: Report of 2 Cases.

Endometrial carcinoma is the most frequent of gynecological cancers, and its treatment is primarily dictated by the identification of molecular alterations, which distinguish four subgroups, each one associated with a specific prognosis. In this article, we report, to our knowledge for the first time, 2 cases of endometrial endometrioid carcinoma exhibiting particular eosinophilic cells and associated with a BRAF mutation. Both patients, women with post-menopausal bleeding, underwent endometrial resection. For the first patient, the examination of the specimen demonstrated a low-grade endometrioid endometrial carcinoma with an associated component of micropapillary structures composed of atypical eosinophilic cells. The resection of the second patient revealed endometrial intraepithelial neoplasia, which was also associated with atypical eosinophilic cells. Molecular analysis of both samples revealed BRAF mutations, specifically p.G469A and p.D594N. The link between the presence of eosinophilic cells and BRAF mutation was previously reported in cases of ovarian serous borderline tumors, which are at a lower risk of progressing toward low-grade serous ovarian carcinoma. The presence of this eosinophilic cell population may help identify endometrial carcinomas harbouring BRAF mutations. Still, this association remains preliminary and merits confirmation in larger cohorts, ideally coupled with functional models.