Fig. 2.

 Cytologic views of post-brushing biliary lavage fluid (Papanicolaou stain, original magnification × 400). a Normal biliary epithelial cells (class I) appearing as a sheet of benign epithelium. The sheet consists of regularly ordered, homogeneous cuboidal cells. b Benign biliary epithelial cells with cellular atypia (class III) appearing as a cluster of inflammatory cells and epithelial cells with enlarged nuclei and architectural disorganization. c A cluster of adenocarcinoma cells (class V) appearing as nested epithelial cells with significantly enlarged nuclei and irregular nuclear margins.