Normal cells

Normal cells are commonly seen in the cytologic specimens of the liver. Hepatocytes, bile duct epithelium, Kupffer cells and sheets of mesothelial cells are often observed in the cytologic preparations.

Hepatocytes - cytologic features

• Large polygonal cells
• Isolated cells, thin ribbons (trabeculae), or larger tissue fragments
• Centrally placed, round to oval nuclei, binucleation, prominent nucleoli, nuclear pseudoinclusions
• Abundant granular cytoplasm
• Pigment
  • Lipofuscin (a normal pigment related to cellular aging) – golden with the Papanicolaou
    stain and green-brown with a Romanowsy-type stain
  • Hemosiderin – dark brown with the Papanicolaou stain and blue with a Romanowsky-type
    stain
  • Bile (in cholestasis) – dark green with both Papanicolaou and Romanowsky stains

Bile duct epithelium - cytologic features

• Cohesive flat sheets
• Cuboidal cells (smaller than hepatocytes)
• Evenly spaced nuclei (‘honeycomb appearance’)

Kupffer cells - cytologic features

• Vacuolated cytoplasm (resembling macrophages)
• Possibly pigment (most commonly hemosiderin)

Differential diagnosis

• Hepatic adenoma
• Focal nodular hyperplasia
• Regenerative nodule in cirrhosis
• Nodular transformation of the liver
• Steatosis

These conditions should be considered when an FNA is composed entirely of normal liver cells (predominantly hepatocytes) and the patient has a focal lesion. In steatosis (fatty metamorphosis), many hepatocytes have large cytoplasmic vacuoles filled with lipids. It is observed with toxic-metabolic injuries of the liver, such as with alcohol consumption, diabetes, obesity, drugs, hepatitis C.