Immunohistochemistry for differentiation of pleural epithelioid malignant mesothelioma from adenocarcinoma: A panel for selection

Abstract

Objective: An important difficulty pathologists confront concerning thoracic pathology is the differentiation of pleural epithelioid malignant mesothelioma from pulmonary adenocarcinoma infiltrating into the pleura or metastatic adenocarcinoma. Since epithelioid malignant mesothelioma may depict microscopic patterns similar to adenocarcinoma, morphological findings may not be sufficient to make a differential diagnosis. Up to now, many immunohistochemical markers have been proposed for their differentiation and there have been many studies on the sensitivity and specifity of each marker.Material and Method: In this study we retrospectively evaluated the reports on patients diagnosed as pleural epithelial MM and patients diagnosed as adenocarcinoma infiltrating into the pleura for the past seven years and determined the immunohistochemical markers used for differential diagnosis.Results: Most frequently used markers were calretinin and CK5/6 for epithelioid malignant mesothelioma and CEA, CD15 and TTF-1 for adenocarcinoma. EMA was used in both groups.Conclusion: We found that a panel including calretinin and CK5/6 for malignant mesothelioma and CEA and CD15 for adenocarcinoma and additionally EMA and TTF-1 avoided the difficulty in all cases. We consider that, if there is any inconsistency between the results of staining with these six markers, other antibodies should be incorporated into the panel.