MUC21 is a novel, negative immunohistochemical marker for epithelioid mesothelioma for its differentiation from lung adenocarcinoma.

AIMS: The process of differential diagnosis between epithelioid mesothelioma and lung adenocarcinoma has been progressing; however, there are no absolute immunohistochemical markers to definitively diagnose epithelioid mesothelioma. The aim of this study was to search for a novel negative marker of epithelioid mesothelioma.

MATERIALS AND METHODS: We immunohistochemically studied the applicability of mucin 21 (MUC21), which was identified in our previous study, as a novel, negative diagnostic marker for epithelioid mesothelioma. Seventy epithelioid mesothelioma and 70 lung adenocarcinoma cases were investigated for the expression of MUC21, along with other previously reported markers, by immunohistochemistry.

RESULTS: MUC21 was expressed in only 2 of the 70 (3%) epithelioid mesothelioma cases, compared to 67 of the 70 (96%) lung adenocarcinoma cases. The sensitivity, specificity, and accuracy of negative MUC21 expression to differentiate epithelioid mesothelioma from lung adenocarcinoma were 97%, 96%, and 96%, respectively, which are similar to those of carcinoembryonic antigen and claudin-4, and better than those of thyroid transcription factor-1, napsin-A, and mucin 4.

CONCLUSION: MUC21 could be used as an additional, novel, negative immunohistochemical marker to differentiate mesothelioma from lung adenocarcinoma. This article is protected by copyright. All rights reserved.