We report the case of a 54-year-old female with dedifferentiated carcinoma of the ovary. Grossly, both ovaries were affected by a tumor of up to 25 mm (right ovary) and 220 mm (left ovary) in diameter. Microscopically, the tumors of both ovaries showed features of well differentiated endometrioid carcinoma with mucinous differentiation. Moreover, in the left ovary there was an undifferentiated solid component consisting of larger cells. Immunohistochemically, the undifferentiated component showed diffuse vimentin positivity and focal expression of cytokeratin 18. Other markers examined including PAX8, estrogen receptors and progesterone receptors were all negative. Dedifferentiated carcinomas consist of an undifferentiated epithelial component and a component of endometrioid carcinoma of FIGO grade 1 or 2. Clinically, they represent aggressive tumors with unfavorable prognosis mostly occurring in the endometrium. To the best of our knowledge, thus far only 6 cases arising in the ovary have been reported in the literature.
Keywords: ovarian carcinoma - dedifferentiated carcinoma - undifferentiated carcinoma - low-grade endometrioid carcinoma..