title: HER2 Protein Overexpression and Gene Amplification in Plasmacytoid Urothelial Carcinoma of the Urinary Bladder.
abstract: OBJECTIVE
  HER2 overexpression has been reported in a minority of urothelial carcinomas, but little is known about HER2 protein expression and gene alterations in plasmacytoid urothelial carcinoma, a rare and aggressive variant. The aim of this study was to clarify the HER2 status in plasmacytoid urothelial carcinomas.
  
  
  METHODS
  Six cases of plasmacytoid urothelial carcinoma were included, in which we evaluated HER2 protein expression by immunohistochemistry (IHC) and HER2 gene amplification by fluorescence in situ hybridization (FISH).
  
  
  RESULTS
  The patients' ages ranged from 57 to 83 years (mean age, 71 years). Five patients were male and one was female. The ratio of the plasmacytoid component ranged from 30% to 100% (mean, 77%). HER2 expression score was 3+ in 4 cases, 2+ in one case, and negative in one case. HER2 gene amplification was positive in 3 cases, of which 2 cases showed a 3+ HER2 IHC score but one case was negative for HER2 IHC. Another 2 cases showed equivocal HER2 FISH results, and one remaining case was negative for HER2 FISH.
  
  
  CONCLUSIONS
  Our observation that plasmacytoid urothelial carcinomas frequently demonstrated HER2 protein overexpression provides supporting evidence that HER2 may be a potential therapeutic target for plasmacytoid urothelial carcinoma.
authors.affiliation: Department of Pathology, Seoul National University College of Medicine, Seoul 03080, Republic of Korea.
authors.forename: Bohyun
authors.initials: B
authors.lastname: Kim
authors.affiliation: Department of Pathology, Seoul National University College of Medicine, Seoul 03080, Republic of Korea.
authors.forename: Gilhyang
authors.initials: G
authors.lastname: Kim
authors.affiliation: Department of Pathology, Seoul National University College of Medicine, Seoul 03080, Republic of Korea.
authors.forename: Boram
authors.initials: B
authors.lastname: Song
authors.affiliation: Department of Pathology, Seoul National University College of Medicine, Seoul 03080, Republic of Korea.
authors.forename: Cheol
authors.initials: C
authors.lastname: Lee
authors.affiliation: Department of Pathology, Seoul National University College of Medicine, Seoul 03080, Republic of Korea.
authors.forename: Jeong Hwan
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Pathology, Seoul National University College of Medicine, Seoul 03080, Republic of Korea; Kidney Research Institute, Medical Research Center, Seoul National University College of Medicine, Seoul 03080, Republic of Korea.
authors.forename: Kyung Chul
authors.identifier: 0000-0002-1969-8360
authors.initials: KC
authors.lastname: Moon
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002295:Carcinoma, Transitional Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005260:Female; D005784:Gene Amplification; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D008875:Middle Aged; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism*; D015854:Up-Regulation; D001749:Urinary Bladder Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human