[617] Napsin-A Expression in Esophageal and Gastric Adenocarcinoma Affected by Choice of Primary Antibody

Michael W Cruise, Elizabeth A Montgomery, Jon M Davison, Reetesh K Pai, Aatur D Singhi. Johns Hopkins University, Baltimore, MD; University of Pittsburgh Medical Center, Pittsburgh, PA

Background: Distinguishing between a primary lung and esophageal adenocarcinoma can be challenging, especially in small biopsies and EUS, and a reliable IHC stain would be helpful. Napsin-A is normally expressed in the cytoplasm of type II pneumocytes and has been reported to be a sensitive and specific marker for primary lung adenocarcinomas. Recently, napsin-A expression has also been demonstrated in papillary renal cell and thyroid carcinoma. However, there are no published studies examining napsin-A expression in esophageal adenocarcinomas.
Design: A total of 1088 esophageal and 215 gastric adenocarcinoma resection specimens were identified and confirmed to be esophageal or gastric primary adenocarcinoma. FFPE tissue sections were stained with a monoclonal antibody (Clone IP64, cat# NCL-L-Napsin A; Leica Biosystems) and a polyclonal antibody (rabbit polyclonal, cat# 352A; Cell Marque) against napsin-A. Of note, both of these antibodies are utilized in clinical labs. Strong granular cytoplasmic staining was interpreted as positive.
Results: The mean age of the patient population is 64 and there was a male predominance with most of the patients having stage III or IV disease. Evaluation of the esophageal adenocarcinomas with the polyclonal antibody demonstrates cytoplasmic staining in 36% of the specimens. In contrast, the monoclonal antibody was negative, only labeling the control lung tissue. Interesting, only 2 of the gastric tumors were positive for napsin-A by the polyclonal antibody but all were negative by with the monoclonal antibody. Panel A of the figure demonstrates the H&E of an esophageal adenocarcinoma and Panel B demonstrates the corresponding labeling by the polyclonal napsin-A antibody.

Conclusions: The usefulness of Napsin-A in determining the differential diagnosis between esophageal adenocarcinoma and pulmonary adenocarcinomas appears to be related with the primary antibody used. Specifically, the monoclonal antibody against napsin-A did not stain the tumors while the polyclonal antibody labeled greater than 1/3 the esophageal adenocarcinomas. Importantly, the expression of napsin-A, as demonstrated by the polyclonal antibody, did not correlate with stage or progression of the disease.
Category: Gastrointestinal

Monday, March 4, 2013 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 92, Monday Morning


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