Table 3.

Overview of CK7, CK19 and CD34 characteristics

Glycoprotein	Function
CK 7	Cytokeratin 7 is a protein belonging to the type I Keratin family, and is used to identify bile-ducts. The keratins are intermediate filament proteins responsible for the structural integrity of epithelial cells. CK 7 in hepatocytes is upregulated by cholestasis and therefore an upregulation of CK 7 is seen in areas with dedifferentiation of normal hepatocytes to bile-ducts (ductular metaplasia) and areas with bile-duct proliferation
CK 19	Cytokeratin 19 is also a protein belonging to the type I Keratin family, and is also called a bile-duct type keratin. In the liver CK 19 is expressed by well-differentiated (native) bile-ducts and can therefore be present in focal nodular hyperplasia. CK 19 expression can therefore be observed in areas with pre-existent bile-ducts and ductular proliferation
CD34	CD 34 is a cell surface glycoprotein that functions as cell–cell adhesion factor. CD 34 is expressed by (premature) hematopoietic and vascular associated tissue. CD 34 expression by sinusoid endothelial cells is associated to the process of angiogenesis. Diffuse expression of CD 34 is a sign of carcinogenesis and is seen in hepatocellular carcinoma. Non-diffuse expression of CD34 can be seen in FNH in areas with sinusoidal proliferation