title: Glutamine Synthetase Immunoreactivity in Peritumoral Hyperplasia in Liver:  Case Report of a Metastatic Paraganglioma With Focal Nodular Hyperplasia-Like Changes and Review of an Additional 54 Liver Masses.
abstract: OBJECTIVE
  Focal nodular hyperplasia (FNH) and peritumoral hyperplasia in the liver exhibit increased immunoreactivity for glutamine synthetase (GS). We observed FNH-like changes with map-like GS staining surrounding a metastatic paraganglioma and sought to determine how often such changes occur around primary and metastatic liver lesions.
  
  
  METHODS
  We performed GS immunohistochemistry in liver cases of 20 metastatic neuroendocrine carcinomas (NECs), 21 metastatic colon carcinomas (CCs), seven hepatocellular carcinomas (HCCs), and six FNHs and assessed lesions for size, degree of fibrosis (scored 1-3), and peritumoral hyperplasia.
  
  
  RESULTS
  Most NEC or CC cases had few peritumoral hyperplastic features. Three NECs, two CCs, and one HCC (13%) had patchy GS staining at the periphery of the lesions. One CC case had both histologic and immunohistochemical peritumoral hyperplasia.
  
  
  CONCLUSIONS
  Peritumoral hyperplasia or FNH-like changes are uncommon findings around primary or metastatic lesions in the liver. GS immunohistochemistry assists in distinguishing true peritumoral hyperplasia from mass effect.
authors.affiliation: From the University of Washington Medical Center, Seattle.
authors.forename: Bronwyn H
authors.initials: BH
authors.lastname: Bryant
authors.affiliation: University of Vermont College of Medicine, Burlington.
authors.forename: Maryam J
authors.initials: MJ
authors.lastname: Zenali
authors.affiliation: From the University of Washington Medical Center, Seattle.
authors.forename: Paul E
authors.initials: PE
authors.lastname: Swanson
authors.affiliation: From the University of Washington Medical Center, Seattle.
authors.forename: Melissa P
authors.initials: MP
authors.lastname: Upton
authors.affiliation: From the University of Washington Medical Center, Seattle.
authors.forename: Matthew M
authors.initials: MM
authors.lastname: Yeh
authors.affiliation: From the University of Washington Medical Center, Seattle.
authors.forename: Carlos
authors.initials: C
authors.lastname: Cuevas
authors.affiliation: From the University of Washington Medical Center, Seattle.
authors.forename: James O
authors.initials: JO
authors.lastname: Park
authors.affiliation: From the University of Washington Medical Center, Seattle mwest2@uw.edu.
authors.forename: Maria
authors.initials: M
authors.lastname: Westerhoff
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000556:secondary; D000328:Adult; D014408:Biomarkers, Tumor / Q000032:analysis*; D006528:Carcinoma, Hepatocellular / Q000175:diagnosis / Q000556:secondary; D003110:Colonic Neoplasms / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D020518:Focal Nodular Hyperplasia / Q000175:diagnosis*; D005974:Glutamate-Ammonia Ligase / Q000032:analysis / Q000096:biosynthesis*; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000175:diagnosis* / Q000201:enzymology / Q000556:secondary*; D010236:Paraganglioma, Extra-Adrenal / Q000175:diagnosis* / Q000556:secondary
chemical_list: D014408:Biomarkers, Tumor; D005974:Glutamate-Ammonia Ligase
keywords: Focal nodular hyperplasia; Glutamine synthetase; Liver metastasis; Mass effect; Paraganglioma; Peritumoral hyperplasia