MSLN and carcinosarcoma: MSLN exhibits heterogeneous expression in endometrial cancer, with varying positivity rates across different histological subtypes: the highest MSLN positivity rate is found in clear cell carcinoma (71.4%), followed by serous carcinoma (56.5%) and carcinosarcoma (50.0%); whereas in endometrioid carcinoma, the positivity rate ranges from 45.5% to 59%.57