Endometrial giant cell carcinoma: new insights from a morphological, immunohistochemical, and molecular analysis of three cases

Herein, we present a morphological, immunohistochemical, and molecular analysis of three cases of endometrial giant cell carcinoma (EGCC) with a literature review. Patient age was 55 to 76 years. The tumors were limited to the uterus and showed dyshesive, bizarre giant cells with numerous atypical mitoses. Minor components were low-grade endometrioid, spindled/myxoid (case nos. 1 and 2), serous (case no. 3), and undifferentiated (all cases). The giant cells were e-cadherin-, cytokeratins/EMA + (focal/multifocal), hormone receptors + (focal/multifocal), vimentin + , p16 + (diffuse), CD68-, α-FP-, β-HCG-, muscle markers-, CD10-, and ERG-. Case no. 3 was p53-abnormal. All cases were mismatch repair-proficient and microsatellite-stable. No POLE mutations were detected. Based on our and previous reports, EGCC is often accompanied by a conventional carcinomatous component (mostly endometrioid) and shows partial loss epithelial markers and negativity for specific differentiation markers. EGCC shows evident similarities to both undifferentiated/dedifferentiated carcinoma and carcinosarcoma and should be managed similarly. Unlike the latter two, EGCC might preferentially derive from "no-specific-molecular-profile" carcinomas.