Cytologic features of hepatic fibrosis in dogs: a retrospective study on 22 cases

Liver cytology has diagnostic value for the identification of neoplastic and nonneoplastic hepatic diseases. However, so far the diagnosis of fibrotic changes has traditionally been restricted to histopathology. Objectives The aim of this study was to describe the cytologic features that may help in the recognition of hepatic fibrosis. Materials and methods Cytologic smears from the liver of dogs histologically diagnosed with hepatic fibrosis (Group A) were selected and compared to liver smears from dogs without hepatic fibrosis (Group B). A differential count of hepatocytes, spindle cells, mast cells, granulocytes, lymphocytes/plasma cells, and macrophages was documented for each case, and means for the fibrosis and nonfibrosis group were compared. Results The relative and total numbers of spindle cells and mast cells were significantly higher in the fibrosis group than in the nonfibrosis group. The optimal cutoff point for the spindle cells to hepatocytes ratio was 0.107 (ie, one spindle cell per 10 hepatocytes), with 95.5% sensitivity and 100% specificity for the cytologic diagnosis of hepatic fibrosis. The optimal cutoff point for the ratio mast cells to hepatocytes was 0.04 (ie, 4 mast cells per 100 hepatocytes) with 86.4% sensitivity and 90% specificity. Discussion The presence of relatively and absolutely increased numbers of spindle and mast cells in hepatic cytology provides a rational basis to identify fibrosis of hepatic parenchyma. Based on a reasonable sensitivity and specificity, the cytologic diagnosis of hepatic fibrosis seems feasible.