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.