Diagnostic utility of sialosyl-Tn in discriminating carcinomatous cells from benign mesothelium in body cavity effusions.
OBJECTIVE
Detecting malignant cells in the setting of reactive mesothelium can be difficult. Several techniques have been tried but without widespread acceptance. Sialosyl-Tn (STn) is an aberrantly glycosylated precursor of the MN blood group antigen frequently expressed in carcinomas and dysplastic epithelium. We investigated the STn monoclonal antibody for its clinical utility as an isolated stain to discriminate benign mesothelium from malignant cells.


METHODS
Cell block material from 72 cases of body cavity fluids were immunostained for STn using the avidin-biotin complex method without antigen retrieval. Slides were incubated overnight at 4 degrees C in a humidified chamber.


RESULTS
Strong immunoreactivity was noted in 31/40 (77%) carcinomatous cases. Only moderate staining was noted in 1 of 28 (4%) benign effusions and weak staining in 5 (18%) additional benign cases. Specificity was 100%, sensitivity 78%, positive predictive value 100% and negative predictive value 76%. No staining was noted in four noncarcinomatous malignant effusions.


CONCLUSIONS
STn may have diagnostic value in this cytologic setting as part of a diagnostic panel but not as an isolated stain.
Zimmerman
R L
RL
Department of Pathology, University of Pennsylvania Health System, Philadelphia, USA. robertz@mail.med.upenn.edu
Fogt
F
F
Bibbo
M
M
D015295:Antigens, Tumor-Associated, Carbohydrate; D001202:Ascitic Fluid / Q000473:pathology*; D014408:Biomarkers, Tumor; D002277:Carcinoma / Q000276:immunology*; D003937:Diagnosis, Differential; D004847:Epithelial Cells; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D016066:Pleural Effusion, Malignant / Q000473:pathology*
D015295:Antigens, Tumor-Associated, Carbohydrate; D014408:Biomarkers, Tumor; C055491:sialosyl-Tn antigen