Usefulness of Maspin Immunostaining in Distinguishing Adenocarcinoma from Benign Epithelium in Endoscopic Bile Duct Biopsies.
Eric A Himmelfarb, Fan Lin, Hanlin L Wang. Cedars-Sinai Medical Center, Los Angeles, CA; Geisinger Medical Center, Danville, PA
Background: Small samples, crush artifact, and a propensity for marked inflammatory and reactive changes following stent placement present challenges in the histologic distinction between benign and malignant epithelium in bile duct biopsies. Overexpression of maspin, a serine protease inhibitor, has been demonstrated in pancreaticobiliary malignancies. However, these studies have largely utilized resection and autopsy specimens. The current study aimed to examine the ability of maspin to distinguish benign from malignant epithelium in endoscopic bile duct biopsies.
Design: A total of 134 endoscopic bile duct biopsies collected between 2006 and 2010 were included in this study. These included 45 adenocarcinomas, 30 atypical cases and 59 benign cases. Immunohistochemistry was performed on formalin-fixed, paraffin-embedded tissues using a monoclonal antibody to maspin. The staining extent, intensity and pattern were assessed by two observers.
Results: Maspin immunoreactivity was observed in cases in all three diagnostic categories, but was more frequently detected in malignant biopsies than in benign cases (P=0.0016). In comparison with benign cases, malignant biopsies also more frequently showed diffuse (P=0.0063) and strong or intermediate (P=0.0344) staining patterns. In addition, positive staining in malignant biopsies tended to be combined nuclear and cytoplasmic, a pattern less commonly seen in benign biopsies, although this difference was not statistically significant (P=0.0586). The staining characteristics for atypical biopsies closely resembled those for malignant biopsies, which were largely attributed to 20 (67%) of the cases that were subsequently diagnosed with adenocarcinomas during followup.
|Malignant (n=45)||Atypical (n=30)||Benign (n=59)|
|Staining Extent (%)||D||44||27||14|
|Staining Intensity (%)||S||22||20||3|
|Staining Pattern (%)||N/C||80||73||48|