In a study of individuals living in a subtropical region in which an irrigation project has been completed, it is noted that rice farmers have experienced an increased rate of an infectious illness since the project began. Investigators determined that the infection is acquired through cercariae that penetrate the skin. The cercariae are released from snails living in the irrigation canals. Infected individuals develop progressive ascites. Which of the following pathologic findings is most likely to be present in these infected individuals as a consequence of the infection?