The sensitivity, specificity and accuracy of negative MUC21 expression for differentiating epithelioid mesothelioma from lung adenocarcinoma were 97%, 96%, and 96%, respectively; these are similar to those of carcinoembryonic antigen and claudin-4, and better than those of thyroid transcription factor-1, napsin-A, and mucin 4.
In conclusion, MUC4 immunohistochemistry is useful for differentiation of epithelioid mesothelioma from lung carcinoma, either adenocarcinoma or squamous cell carcinoma.