[1685] IgM Positive Plasma Cells Can Distinguish Primary Biliary Cirrhosis from Autoimmune Hepatitis in Cirrhotic Livers

Maylee Hsu, Paul E Swanson, Matthew Yeh. University of Washington, Seattle, WA

Background: Primary biliary cirrhosis (PBC) and autoimmune hepatitis (AIH) have similar histologic features, both characterized by dense lymphoplasmacytic portal inflammation. These two diseases may be difficult to distinguish on histology, particularly in end-stage liver. Recent studies have shown that IgG and IgM immunostaining can differentiate AIH from PBC in needle core biopsies; however, it remains unclear if this distinction also applies in cirrhotic liver.
Design: Explanted livers of 20 PBC and 18 AIH cases, each histologically and clinically proven, were included. Immunohistochemistry for IgM and IgG was performed on representative blocks using a polymer-based detection system. The numbers of IgM and IgG positive plasma cells in three representative high power (40X) fields per slide were counted.
Results: The average number of IgG positive plasma cells was 1.87 and 2.69 in PBC and AIH cases, respectively. The average number of IgM positive plasma cells was 6.13 and 1.87 in PBC and AIH cases, respectively. The difference in IgM positive cells was statistically significant (p=0.001). IgM positive plasma cells outnumbered IgG positive plasma cells in 17/20 (85%) PBC cases and in 7/18 (39%) AIH cases (p= 0.006).
Conclusions: Our study extends the known utility of IgM immunohistochemistry in the separation of PBC and AIH in needle core biopsies by demonstrating that the absolute number of IgM plasma cells is also greater in explants of cirrhotic PBC when compared to end stage AIH liver explants. These findings may be of particular clinical utility in the evaluation of end-stage cryptogenic cirrhosis.
Category: Liver

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 159, Tuesday Afternoon


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