Background and objectives: Endometrial carcinoma is a common cancer among women. The endometrioid type of carcinoma usually has a better prognosis than uterine serous carcinoma (USC). Diagnosis may be challenging as not all USCs have a papillary architecture, and some endometrioid adenocarcinomas (EACs) may manifest as solid sheets of tumor cells, especially of high grade. The aim of this study was to evaluate the combination of insulin-like growth factor II messenger RNA-binding protein 3 (IMP3) and claudin-1 immunostaining in differentiation between both tumors.
Materials and methods: Histopathological evaluation of 86 archival EAC, 20 USC, 10 endometrial hyperplasia, eight atypical endometrial hyperplasia, and two endometrial intraepithelial carcinoma patients was carried out. Immunohistochemical evaluation of IMP3 and claudin-1 expression was carried out by progesterone (PR) and P53 immunostaining in challenging cases.
Results: There was a significant difference between IMP3 and claudin-1 in EAC patients, whereas all patients with USC were IMP3+/claudin-1+. In one of the patients with a challenging case of EAC, the diagnosis was changed to USC as the patient was IMP3+/claudin-1+, as well as P53+/PR−. All challenging cases of USC were IMP3+/claudin-1+ and P53+/PR−; hence, their diagnosis was confirmed. Both endometrial intraepithelial carcinoma patients were IMP3+/claudin-1+, whereas all nonatypical endometrial hyperplasia patients were IMP3−/claudin-1−.
Conclusion: Combined use of IMP3 and claudin-1 is useful in differentiating between EAC and USC, especially in diagnostically challenging cases.