This is a reticulin stain of a liver biopsy; notice the grey stained lines that demarcate vascular endothelium. This is a helpful stain to use when the diagnosis of hepatocellular carcinoma is being entertained.
Sometimes we are fortunate to see the classic features of neoplasia like hyperchromacia, increased nuclear to cytoplasmic ratio, or cellular asymmetry and crowding. However, HCC is sometimes very well-differentiated, and those features on routine H&E staining are absent. This is where reticulin stains come in handy.
Normal hepatic architecture has one or two cell ‘plates’ of thickness between each endothelial border. If tissue is dysplastic, dividing cells no longer recognize their boundaries. You will see multiple plates of cells between the reticulin stains. In this image, you can count 4, 5 and even 6 hepatocytes in between the reticulin stains…that’s not good. That’s HCC.