Histopathologic evaluation of feline inflammatory liver disease.

To better define the histopathologic features of feline inflammatory liver disease, we studied feline liver biopsies evaluated at the University of Minnesota Veterinary Teaching Hospital over a 10-year period. Of 175 liver sections examined, 45 had portal inflammatory infiltrates. Of these, 60% had infiltrates consisting of lymphocytes and plasma cells, 24% had infiltrates consisting of neutrophils, and 16% had mixed infiltrates consisting of neutrophils, lymphocytes, and plasma cells. Lymphocytic-plasmacytic portal infiltrates were characterized by various degrees of bile duct proliferation and fibrosis without evidence of bile duct infiltration or periportal necrosis. Sections with portal neutrophilic infiltrates were characterized by bile duct infiltration, bile duct epithelial degeneration, periportal necrosis, and infiltration of neutrophils into adjacent lobules. We propose that hepatitis characterized by portal lymphocyte and plasma cell infiltration be termed lymphocytic portal hepatitis and that hepatitis characterized by cholangitis and portal neutrophilic infiltrates with or without lymphocytes and plasma cells be termed cholangiohepatitis.