title: PAX2 and PAX8 expression in primary and metastatic renal tumors: a comprehensive comparison.
abstract: BACKGROUND
  The diagnosis of renal cell carcinoma (RCC) remains problematic, especially in the context of metastasis or small-needle biopsies. PAX2 and PAX8 transcription factors are known to be expressed by several histologic types of renal neoplasms.
  
  
  OBJECTIVE
  To evaluate the diagnostic utility of PAX2 and PAX8 relative to one another, which has not been studied.
  
  
  METHODS
  Consecutive tissue sections from the archival samples of 243 primary and 99 metastatic renal neoplasms were submitted to PAX2 and PAX8 immunostain.
  
  
  RESULTS
  Within the primary neoplasms, PAX2 versus PAX8 expression was noted in 90 of 95 (95%) versus 92 of 95 (97%) for clear cell RCC, 29 of 38 (76%) versus 38 of 38 (100%) for papillary RCC, 14 of 25 (56%) versus 22 of 25 (88%) for chromophobe RCC, 3 of 7 (43%) versus 5 of 7 (71%) for collecting duct RCC, 6 of 8 (75%) versus 8 of 8 (100%) for acquired cystic kidney disease-related RCC, and 7 of 13 (54%) versus 11 of 13 (85%) for oncocytoma. Regardless of histologic subtype, PAX8 staining was noted in more cells and with more intense staining than PAX2. Within the metastatic RCCs, PAX8 expression was more frequently positive than PAX2 expression (88 of 99 cases; 89%; versus 75 of 99 cases; 76%).
  
  
  CONCLUSIONS
  Both PAX2 and PAX8 are diagnostically useful markers for both primary and metastatic renal neoplasms of a large variety of histologic types. However, PAX8 appears to be more sensitive than PAX2 in both primary and metastatic settings. PAX8 can be included in any immunohistochemical panel for the diagnosis of primary renal neoplasms. Adding PAX2 should be optional, but this would gain limited further diagnostic yield. In a metastatic setting, both PAX8 and PAX2 can be included in a panel because a small subset of metastatic RCCs are stained only with PAX2.
authors.affiliation: Department of Pathology, The Methodist Hospital, Houston, Texas, USA. aozcan06018@gmail.com
authors.forename: Ayhan
authors.initials: A
authors.lastname: Ozcan
authors.forename: Gustavo
authors.initials: G
authors.lastname: de la Roza
authors.forename: Jae Y
authors.initials: JY
authors.lastname: Ro
authors.forename: Steven S
authors.initials: SS
authors.lastname: Shen
authors.forename: Luan D
authors.initials: LD
authors.lastname: Truong
mesh_terms: D018249:Adenoma, Oxyphilic / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology / Q000556:secondary; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001706:Biopsy; D002291:Carcinoma, Papillary / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology / Q000556:secondary; D002292:Carcinoma, Renal Cell / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology / Q000556:secondary; D003937:Diagnosis, Differential; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D007668:Kidney / Q000378:metabolism* / Q000473:pathology; D052177:Kidney Diseases, Cystic / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D007680:Kidney Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology / Q000556:secondary; D007685:Kidney Tubules, Collecting / Q000378:metabolism / Q000473:pathology; D009363:Neoplasm Proteins / Q000378:metabolism*; D051762:PAX2 Transcription Factor / Q000378:metabolism*; D000072636:PAX8 Transcription Factor; D051761:Paired Box Transcription Factors / Q000378:metabolism*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins; D051762:PAX2 Transcription Factor; C497318:PAX2 protein, human; D000072636:PAX8 Transcription Factor; C083325:PAX8 protein, human; D051761:Paired Box Transcription Factors