| Abstract: | BACKGROUND: Autoimmune hepatitis (AIH) is a non-resolving inflammatory liver disease. Inflammation showing plasma cells under hematoxylin-eosin (H&E) stain is typical of AIH. In many cases, however, only lymphocytes and occasional granulocytes are found. It was recently noticed that the antibody to multiple myeloma oncogene 1/IRF4 (MUM1), stained plasma cells and their precursors. PATIENTS AND METHODS: Liver biopsies from 11 patients were stained with H&E and with anti-MUM1. Clinically, four patients were suspicious of AIH, four had viral hepatitis C, two nonalcoholic steatohepatitis (NASH) and one, fatty liver. Counting was performed in three high-power fields. RESULTS: In patients having clinical suspicion of AIH, H&E revealed plasma cells in only one of the four cases. On the other hand, MUM1 immunostain revealed such cells in all four cases, MUM1-expressing cells were found in the portal triads, in the zone corresponding to interface inflammation and in the parenchyma surrounding the interface hepatitis. MUM 1-expressing cells ranged from 26 to 44 in AIH, from 2 to 15 in viral hepatitis C, from 1 to 3 in NASH, and from 0 to 2 in the case with fatty liver (AIH vs. viral hepatitis C/NAS/fatty liver, p<0.05). CONCLUSION: These preliminary results suggest that MUM1 immunostain may be of help in endorsing a presumptive clinical diagnosis of AIH and may add valuable information in the differential diagnosis between AIH and the other liver diseases examined here. This appears to be the first report in which MUM1 immunostain has been applied to assess the presence of plasma cell precursors in AIH. |
