Immunocytochemical study of the expression of mesothelin in fine‐needle aspiration biopsy specimens of pancreatic adenocarcinoma

Abstract

Mesothelin is a potential marker of pancreatic adenocarcinoma that was recently identified by serial analysis of gene expression. We evaluated the sensitivity and specificity of mesothelin as a marker of pancreatic adenocarcinoma on destained Papanicolaou (Pap) smears and unstained cellblocks from 28 patients using a monoclonal antibody to mesothelin. Intensity and proportion of staining was semiquantitatively graded on a scale of 1-3, and as 0%, 1 to <10%, 10-50%, or >50%. Positive staining for mesothelin was seen in 64% of the direct smears and in 36% of cell block sections. Focal positivity for mesothelin was noted in benign pancreatic tissue in one of 10 cases. Staining was most often focal (<50% of cells) in both direct smears and cell block sections. The overall sensitivity and specificity of mesothelin as a marker for pancreatic adenocarcinoma were 68% and 90%, respectively. Sensitivity was higher in Pap smears than in cell block sections (64% versus 36%). The presence of occasional mesothelin expression in benign tissue, its very focal expression in malignant tissue may limit the utility of mesothelin as a marker of pancreatic adenocarcinomas in fine-needle aspiration (FNA) specimens.

Expression of KOC, S100P, mesothelin and MUC1 in pancreatico-biliary adenocarcinomas: development and utility of a potential diagnostic immunohistochemistry panel

“…Fourth, most of the IHC diagnostic biomarkers have been investigated individually [32,46,47,55,56], with few studies reporting the utility of biomarker panels [30,36]. We carefully selected candidate biomarkers reported in different studies (KOC, mesothelin, S100P and MUC1) for investigation in a single experimental setting.…”

The usefulness of S100P, mesothelin, fascin, prostate stem cell antigen, and 14‐3‐3 sigma in diagnosing pancreatic adenocarcinoma in cytological specimens obtained by endoscopic ultrasound guided fine‐needle aspiration

“…In the literature, a number of attempts have been made to improve the accuracy of cytology for pancreatic lesions . The level of S100P expression has been found to increase during the progression from PanIN to invasive adenocarcinoma.…”

“…All the other four proteins have been observed to be variously overexpressed in pancreatic ductal carcinoma using histologic specimen . Few studies evaluated PSCA and/or mesothelin in FNA cytology specimen and showed increased accuracy in cytologically borderline cases . Baruch et al noted that the overall sensitivity and specificity of mesothelin were 68% and 90%, respectively and that the role of mesothelin alone as a marker for cytologic confirmation of pancreatic adenocarcinoma is limited by its rare expression in benign tissue, especially gastric epithelium that is a common source of contamination and frequent cause of pitfalls in EUS‐FNA pancreas specimens, as well as focal expression in malignant pancreatic tissue .…”

“…Few studies evaluated PSCA and/or mesothelin in FNA cytology specimen and showed increased accuracy in cytologically borderline cases . Baruch et al noted that the overall sensitivity and specificity of mesothelin were 68% and 90%, respectively and that the role of mesothelin alone as a marker for cytologic confirmation of pancreatic adenocarcinoma is limited by its rare expression in benign tissue, especially gastric epithelium that is a common source of contamination and frequent cause of pitfalls in EUS‐FNA pancreas specimens, as well as focal expression in malignant pancreatic tissue . The normal gastric epithelium is strongly highlighted by S100P protein and is usually restricted to the mucus producing surface epithelial cells and the chief cells of the gastric glands .…”

A quarter century of EUS-FNA: Progress, milestones, and future directions

“…Numerous studies have also reported the usefulness of immunostaining of S100P,[ 246 279 280 281 282 283 284 285 ] mesothelin,[ 285 286 287 288 289 290 ] mucins,[ 287 291 292 293 294 295 ] or KOC/IMP3[ 279 282 296 297 298 ] in EUS-FNA samples. Those reports might help improve the efficacy of EUS-FNA for diagnosis of solid pancreatic masses.…”