title: Expression of carbonic anhydrase IX in genitourinary and adrenal tumours.
abstract: OBJECTIVE
  High expression of carbonic anhydrase IX (CAIX) is reported for clear cell renal cell carcinoma (RCC), with a paucity of data for non-renal genitourinary or adrenal tumours. This study investigated the immunohistochemical expression of CAIX throughout the genitourinary tract and adrenal gland.
  
  
  RESULTS
  High expression in the renal cortex was restricted to clear cell, papillary and clear cell papillary RCC and carcinoid. Core biopsies of clear cell RCC were consistently positive. Positivity within the urothelial tract was seen in urothelial carcinoma including squamous, small-cell, sarcomatoid and adenomatous differentiation and clear cell adenocarcinoma. Signet ring and plasmacytoid variants of urothelial carcinoma were negative. Phaeochromocytoma, adrenal cortical adenoma, seminoma, yolk sac tumour, choriocarcinoma, Leydig cell tumour and prostatic adenocarcinoma were predominately negative, with variable reactivity in adrenal cortical carcinoma, embryonal carcinoma, teratoma and Sertoli cell tumour.
  
  
  CONCLUSIONS
  Carbonic anhydrase IX is a sensitive marker for clear cell RCC in core biopsies. However, other genitourinary or adrenal tumours that can have a clear cell appearance including urothelial, squamous cell, clear cell adeno and adrenal cortical carcinoma and Sertoli cell tumour express CAIX. Knowledge of expression overlap between these entities may prevent incorrect interpretation of immunohistochemical results, particularly if limited tissue is available.
authors.affiliation: Department of Pathology, The Ohio State University Medical Center, Columbus, OH 43210, USA.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Donato
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Johnson
authors.forename: Ximing J
authors.initials: XJ
authors.lastname: Yang
authors.forename: Debra L
authors.initials: DL
authors.lastname: Zynger
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000201:enzymology*; D000951:Antigens, Neoplasm / Q000032:analysis / Q000096:biosynthesis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases / Q000032:analysis / Q000096:biosynthesis*; D002292:Carcinoma, Renal Cell / Q000201:enzymology; D006801:Humans; D007150:Immunohistochemistry; D007680:Kidney Neoplasms / Q000201:enzymology; D008297:Male; D014565:Urogenital Neoplasms / Q000201:enzymology*
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; C089226:CA9 protein, human; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases