Fibrosis is an integral feature of steatohepatitis and is typically seen in perivenular regions (acinar zone 3). Perisinusoidal stellate (Ito) cells deposit collagen as a result of Kupffer cell activation, release of platelet-activating factor, and neutrophilic infiltration. In severe steatohepatitis, the fibrosis extends to involve the remainder of the lobule as well as the portal tracts. Pericellular (“chicken-wire”) fibrosis is characteristic: strands of collagen surround damaged hepatocytes, forming a delicate meshwork that is highlighted by special stains, such as Trichrome or Sirius Red (as seen here). Pericellular fibrosis in the absence other features of steatohepatitis may result from a previous episode of steatohepatitis. Image Copyright: pathorama.ch.