Ovarian-dedifferentiated endometrioid adenocarcinoma: A rare case report

We reported a case of dedifferentiated ovarian carcinoma in a 51-year-old woman. The microscopic tumor consisted of well-differentiated endometrioid carcinoma and undifferentiated carcinoma. Undifferentiated carcinoma was characterized by high-grade nuclear features, mainly solid growth, vacuolar nuclei, frequent nuclear division, and necrosis. Undifferentiated carcinoma did not express epithelial immune markers; p53 was completely deficient in both components; the expression of MMR proteins was only deficient in low-grade endometrioid carcinoma, while it was preserved in undifferentiated carcinoma; SMARCB1/INI1 was diffused expression in both components; SOX2 was diffusely expressed in undifferentiated carcinoma, but not in well-differentiated components; SMARCA4/BRG1 was inactivated in undifferentiated components. These resulted in a poor prognosis.