Dedifferentiated endometrioid adenocarcinoma; clinicopathologic and immunohistochemical features of five cases

Abstract

Objective: Dedifferentiated endometrioid adenocarcinoma is a recently defined uterine tumor composed of low-grade endometrioidadenocarcinoma and undifferentiated carcinoma. Herein, we present clinicopathologic, morphologic, and immunohistochemical features of 5cases of dedifferentiated endometrioid adenocarcinoma.Material and Methods: All cases which were diagnosed as mixed endometrial adenocarcinoma (endometrioid+undifferentiated carcinoma)or dedifferentiated endometrioid adenocarcinoma between January 2008 and December 2014 were retrieved from the archives of our institution’spathology department.Results: The median age of the patients was 58 years. Polypoid growth pattern was seen in 3 patients and 2 were diagnosed at advanced stage.All patients received either external radiotherapy, brachytherapy, chemotherapy or an appropriate combination according to the stage. Onlyone patient died of the disease. Microscopically, there was a sharp demarcation between the two tumor components. The undifferentiatedcarcinoma component was composed of diffuse sheets of monomorphic cells lacking any differentiation. Focal pleomorphism and rhabdoidfeatures were also noted. The undifferentiated carcinoma component was variably positive for PAX-8, cytokeratin, EMA, estrogen receptor, andneuroendocrine markers.Conclusion: Misdiagnosis of undifferentiated carcinoma in dedifferentiated endometrioid adenocarcinoma as grade 3 endometrioidadenocarcinoma is not uncommon. The recognition of morphologic and immunohistochemical features of this newly described entity is crucialbecause it alters treatment and prognosis. (J Turk Ger Gynecol Assoc 2018; 19: 132-6)