All IHC stains will include a positive control tissue

• In normal liver, GS is present in the centrilobular regions of the liver, usually around the central veins
• In FNH of the liver, GS is present in large groups of hepatocytes, in an anastomosing pattern, typically around hepatic veins (referred to as a geographic or "map-like" pattern)
• HA show no staining, focal staining of hepatocytes around central veins, or patchy staining at the periphery (non-uniform and non-intense)
• Diffuse GS staining is seen in 13-70% of early hepatocellular carcinomas (HCC)
• High-grade dysplastic nodules (HGDN) are either GS negative, or show patchy positive staining for GS

Submit a formalin-fixed, paraffin-embedded tissue

Formalin-fixed, paraffin-embedded (FFPE) tissue block

FFPE tissue section mounted on a charged, unstained slide

Ambient (preferred)

• Unlabeled/mislabeled block
• Insufficient tissue
• Slides broken beyond repair

Immunohistochemical staining and microscopic examination

If requested, an interpretive report will be provided

Specifications

• Glutamine synthetase (GS) is an enzyme that converts glutamate and ammonia to glutamine
• GS can be used in a panel with serum amyloid A and beta catenin to help differentiate between hepatic adenomas (HA) and focal nodular hyperplasia (FNH)

Staining pattern

• Strong cytoplasmic staining

References

1. Shafizadeh N et al: Diagnosis of well-differentiated hepatocellular lesions: role of immunohistochemistry and other ancillary techniques. Adv Anat Pathol 2011;18:438-445).
2. Joseph NM et al: Diagnostic utility and limitations of glutamine synthetase and serum amyloid-associated protein immunohistochemistry in the distinction of focal nodular hyperplasia and inflammatory hepatocellular adenoma. Modern Pathology (2014) 27, 62-72; doi:10.1038/modpathol.2013.114.