[1419] IgG and IgM Immunostaining of Inflammatory Cells, Histopathology and Serology in 63 Cases of Overlap Syndrome, Autoimmune Hepatitis and Primary Biliary Cirrhosis, with Special Attention to Overlap Syndrome
H Lee, CK Ma, AH Ormsby, VV Shah. Henry Ford Hospital, Detroit, MI
Background: Autoimmune hepatitis (AIH) - Primary biliary cirrhosis (PBC) Overlap syndrome (OS) is a vaguely defined entity that demonstrates clinical, serological, and histological features of both AIH and PBC, of which the criteria for diagnosis are not standardized. As an extension of a recently published abstract (1), we investigated and compared the IgG and IgM staining pattern in established cases of OS, AIH and PBC focusing on the cases of OS. Serologic data were reviewed.
Design: AIH (26), PBC (26) and OS (11) cases including needle biopsies and hepatectomies were retrieved from the files at Henry Ford Hospital (1998-2008). Representative sections including recuts and tissue microarrays from formalin fixed, paraffin embedded tissue blocks were stained for IgG and IgM. The percentage of IgG or IgM positive inflammatory cells including plasma cells and plasmacytoid lymphocytes was approximated. The degree of inflammation and fibrosis was evaluated using Ishak's scoring system.
Results: IgG positive cells outnumbered IgM positive cells in 6 of 11 OS cases, 4 OS cases showed more IgM positivity, and 1 was equivocal. Anti-mitochondrial antibody (AMA) and anti-nuclear antibody (ANA) and/or anti-smooth muscle antibody (ASMA) were both positive in 2/11 OS, and both negative in 2/11.
| IgG>IgM | IgM IgG | HAI | Fibrosis | AMA positivity | ANA ASMA positivity | |
| OS(n=11) | 6/11 | 5/11 | 6(2-10) | 3 | 3/11 | 7/11 |
| AIH(n=26) | 26/26 | 0/26 | 4(1-7) | 3 | 2/26 | 21/26 |
| PBC(n=26) | 12/26 | 14/26 | 8(2-12) | 3 | 20/26 | 8/26 |
Conclusions: AIH-PBC overlap syndrome does not demonstrate either IgG or IgM predominance (p > 0.2 by Fisher's exact test,) regardless of the degree of inflammation or fibrosis (p > 0.5 by unpaired t-test). HAI of OS is in between that of AIH and PBC. Our findings in the AIH and PBC group validate the findings of the reference study with IgG versus IgM predominance being significantly different in these two groups (p < 0.001). OS appears to be a heterogeneous group with no predictable IgG or IgM predominance in the periportal inflammatory infiltrate. 1. JA Daniels, MS Torbenson, RA Anders, JK Boitnott. IgM and IgG immunostaining differentiates primary biliary cirrhosis from autoimmune hepatitis. Mod Pathol. 2008:21;303A
Category: Liver & Pancreas
Monday, March 9, 2009 2:15 PM
Platform Session: Section E, Monday Afternoon