Histopathological and Immunohistochemical Study of D2-40 Expression in Malignant Pleural Mesothelioma and Metastatic Adenocarcinoma

Abstract Background: Malignant pleural mesothelioma (MPM) is known to be an aggressive malignant tumor due to the difficulty of making early diagnosis and its rapid progression. Its incidence is increasing worldwide but no treatment plans are accepted. D2-40 is an immunohistochemical marker (mono-clonal antibody) that has been used as a lymphatic endothelial marker and used in the differential diagnosis of MPM (epi-thelioid type) versus metastatic adenocarcinoma. Fifty spec-imens of the pleural biopsy were viewed. They were diagnosed as 40 cases of MPM (epithelioid type) and 10 cases of meta-static adenocarcinoma (unknown primary origin). These diagnoses based on Hematoxylin and Eosin (Hx & E) stained sections and other immunohistochemical markers such as calretinin, carcinoembryonic antigen (CEA), thyroid transcrip-tion factor-1 (TTF-1). Aim of Study: To compare D2-40 immunostaining in MPM (epithelioid type) and metastatic adenocarcinoma with deter-mining its sensitivity and specificity in both types. Results: All cases of MPM epithelioid type were positive for D2-40 while all cases of metastatic adenocarcinoma were negative (both sensitivity and specificity= 100%). D2-40 staining result was considered positive or negative according to the presence or absence of membranous staining. Statistical analysis was done for assessment of D2-40 expression in both types of tumors by using SPSS version 21. Conclusion: Routine immunohistochemical work using D2-40 with calretinin is recommended. D2-40 would be superior to calretinin because of its membranous pattern of staining which does not obscure the cytological features of the tumor cells as compared to calretinin.