title: Immunohistochemical reevaluation of carbonic anhydrase IX (CA IX) expression in tumors and normal tissues.
abstract: OBJECTIVE
  To immunohistochemically evaluate the carbonic anhydrase IX (CA IX) expression on 1,551 cases of tumors and normal tissues from various organs.
  
  
  METHODS
  Immunohistochemical evaluation of the expression of CA IX was performed on 1,125 malignant tumors, 69 benign neoplasms, and 322 normal tissues on tissue microarray sections and 18 intrahepatic cholangiocarcinomas (ICCs) and 17 hepatocellular carcinomas (HCCs) on routine sections.
  
  
  RESULTS
  There was overexpression of CA IX in clear cell renal cell carcinoma (CRCC) (88%, 68/77). Twenty-six (90%) of 29 ICCs were positive. In contrast, only 5 (15%) of 34 HCCs were focally positive. No staining was seen in chromophobe renal cell carcinoma (ChRCC), oncocytoma, seminoma, or carcinomas of the breast, thyroid, or prostate. All normal renal tubules except one case showed no staining.
  
  
  CONCLUSIONS
  These data demonstrate the diagnostic utility of CA IX in (1) differentiating CRCC from ChRCC and oncocytomas, (2) distinguishing low-grade CRCC from normal renal tubules in small samples, (3) separating ICC from HCC, and (4) identifying metastatic CRCC from other metastases with clear cell features.
authors.affiliation: Dept of Laboratory Medicine, MC 01-31, Geisinger Medical Center, 100 N Academy Ave, Danville, PA 17822; Flin1@geisinger.edu.
authors.forename: Adelina
authors.initials: A
authors.lastname: Luong-Player
authors.forename: Haiyan
authors.initials: H
authors.lastname: Liu
authors.forename: Hanlin L
authors.initials: HL
authors.lastname: Wang
authors.forename: Fan
authors.initials: F
authors.lastname: Lin
mesh_terms: D000951:Antigens, Neoplasm / Q000032:analysis / Q000096:biosynthesis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases / Q000032:analysis / Q000096:biosynthesis*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009369:Neoplasms / Q000201:enzymology*; D046888:Tissue Array Analysis
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; C089226:CA9 protein, human; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases
keywords: Carbonic anhydrase IX; Cholangiocarcinoma; Clear cell carcinoma of the ovary and uterus; Hepatocellular carcinoma; Normal kidney; Renal cell carcinoma