title: Podoplanin is a better immunohistochemical marker for sarcomatoid mesothelioma than calretinin.
abstract: Immunohistochemistry using a broad panel of markers is an invaluable tool for diagnosing sarcomatoid mesothelioma. Membranous podoplanin staining has been proposed as a specific and sensitive marker to distinguish epithelioid mesothelioma from adenocarcinoma. We found that cytoplasmic podoplanin staining was present in sarcomatoid mesotheliomas, and wanted to explore the reproducibility and specificity of this staining pattern. Immunohistochemistry for podoplanin, using 2 podoplanin antibodies (antipodoplanin and D2-40), was performed in 55 mesotheliomas (24 epithelioid, 18 sarcomatoid, and 13 biphasic), 80 pulmonary adenocarcinomas, 8 synovial sarcomas, and 16 sarcomatoid carcinomas. Expression of calretinin, vimentin, MOC31, and TTF-1 was also examined in all adenocarcinomas, sarcomatoid carcinomas, 7 synovial sarcomas, and 21 of the mesotheliomas. Calretinin staining performed previously on an additional 31 mesotheliomas was reviewed. Using membranous or cytoplasmic staining as indicative of positivity, we found that antipodoplanin and D2-40 each stained 84% of mesotheliomas (antipodoplanin: 46/55; D2-40: 38/44), including 72% of sarcomatoid mesotheliomas (antipodoplanin: 13/18; D2-40: 11/14). With antipodoplanin antibody, no staining was seen in the pulmonary adenocarcinomas (0/80, 0%) or the synovial sarcomas (0/8, 0%), and weak cytoplasmic staining was seen in only 1 sarcomatoid carcinoma (1/15, 7%). D2-40 showed similar results, staining 3% (2/80) of pulmonary adenocarcinomas, 13% (1/8) of synovial sarcomas, and 8% (1/13) of sarcomatoid carcinomas. Overall sensitivities and specificities were 84% and 99% for antipodoplanin, and 86% and 96% for D2-40. These findings suggest that cytoplasmic podoplanin expression may be useful in the diagnosis of sarcomatoid mesothelioma, although it should be used with caution on biopsy material.
authors.affiliation: Department of Pathology, University of Virginia Health System, Charlottesville, VA 22908, USA.
authors.forename: Diana M
authors.initials: DM
authors.lastname: Padgett
authors.forename: Helen P
authors.initials: HP
authors.lastname: Cathro
authors.forename: Mark R
authors.initials: MR
authors.lastname: Wick
authors.forename: Stacey E
authors.initials: SE
authors.lastname: Mills
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology; D014408:Biomarkers, Tumor / Q000032:analysis*; D064032:Calbindin 2; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000473:pathology; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D008654:Mesothelioma / Q000378:metabolism*; D010997:Pleural Neoplasms / Q000378:metabolism*; D015203:Reproducibility of Results; D064030:S100 Calcium Binding Protein G / Q000096:biosynthesis*; D012680:Sensitivity and Specificity; D046888:Tissue Array Analysis; D000098853:Podoplanin
chemical_list: D014408:Biomarkers, Tumor; D064032:Calbindin 2; D008562:Membrane Glycoproteins; D064030:S100 Calcium Binding Protein G; C576764:CALB2 protein, human; C117468:PDPN protein, human; D000098853:Podoplanin