title: Use of mesothelin as a marker for mesothelial cells in cytologic specimens.
abstract: Immunocytochemistry is often employed for the distinction between mesothelial cells and adenocarcinoma. Mesothelin has recently been reported to be expressed in reactive mesothelial cells and epithelioid mesotheliomas. The objective of this study is to determine the utility of mesothelin as marker for mesothelial cells in cytologic preparations. Thirty cell blocks were retrieved from the archives and immunostained with monoclonal antibody directed against mesothelin and calretinin. Heat-induced epitope retrieval technique was employed, and the immunostaining was accomplished using an automated stainer. These tissue blocks were from 35 patients (17 females and 18 males) with a median age of 64 years. Nine were benign effusions, 11 mesotheliomas, and 18 metastatic adenocarcinomas. The presence of any immunoreactivity, irrespective of level of intensity or percentage of cells, was considered positive for mesothelin expression. Follow up included correlation with pathology materials obtained at surgery and review of medical records. Mesothelin staining was positive in 7/9 benign cases, 8/11 mesotheliomas, and 8/18 adenocarcinomas. The difference of mesothelin expression between mesothelial cells and adenocarcinoma was statistically significant. For calretinin, all cases, except 2 malignant mesotheliomas and 3 adenocarcinomas, showed positive staining with calretinin. As a marker for mesothelial cells, the sensitivity and specificity of mesothelin were 73% and 55%, respectively, and the sensitivity and specificity of calretinin were 95% and 86%, respectively. Therefore, mesothelin is not a sensitive or a specific marker for mesothelial cells in cytologic specimens when compared with calretinin.
authors.affiliation: Department of Pathology, University of Alabama, Birmingham, Alabama 35249-6823, USA.
authors.forename: Cornelius
authors.initials: C
authors.lastname: Kachali
authors.forename: Isam
authors.initials: I
authors.lastname: Eltoum
authors.forename: Debra
authors.initials: D
authors.lastname: Horton
authors.forename: David C
authors.initials: DC
authors.lastname: Chhieng
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000378:metabolism; D001202:Ascitic Fluid / Q000473:pathology; D014408:Biomarkers, Tumor / Q000032:analysis*; D064032:Calbindin 2; D005260:Female; D058851:GPI-Linked Proteins; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D000090204:Mesothelin; D008654:Mesothelioma / Q000175:diagnosis* / Q000378:metabolism; D008875:Middle Aged; D010996:Pleural Effusion / Q000473:pathology; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D012680:Sensitivity and Specificity
chemical_list: D014408:Biomarkers, Tumor; C576764:CALB2 protein, human; D064032:Calbindin 2; D058851:GPI-Linked Proteins; D008562:Membrane Glycoproteins; D064030:S100 Calcium Binding Protein G; D000090204:Mesothelin