title: Diagnostic utility of p63/P501S double sequential immunohistochemical staining in differentiating urothelial carcinoma from prostate carcinoma.
abstract: BACKGROUND
  Distinguishing urothelial carcinoma (UC) from prostate carcinoma (PC) is important due to potential therapeutic and prognostic implications. However, this can be a diagnostic challenge when there is limited tissue and in poorly differentiated tumors. We evaluated the diagnostic utility of a dual immunohistochemical stain comprising p63 and P501S (prostein), applied sequentially on a single slide and visualized by double chromogen reaction, in differentiating these two cancers. Thus far, there have been no previous studies assessing the diagnostic utility of p63 and P501S combined together as a dual immunostain in distinguishing between these two cancers.
  
  
  METHODS
  p63/P501S dual-color sequential immunohistochemical staining was performed on archival material from 132 patients with high-grade UC and 23 patients with PC, and evaluated for p63 (brown nuclear) and P501S (red cytoplasmic) expression. Both the staining intensity and percentage of positive tumor cells were assessed.
  
  
  RESULTS
  p63 was positive in 119/132 of UC and negative in PC. P501S was positive in 22/23 of PC and negative in UC. The p63+/P501S- immunoprofile had 90% sensitivity and 100% specificity for UC. The p63-/P501S+ immunoprofile had 96% sensitivity and 100% specificity for PC.
  
  
  CONCLUSIONS
  Our results indicate that double sequential immunohistochemical staining with p63 and P501S is highly specific and can be a useful tool in distinguishing UC from PC especially when there is limited diagnostic tissue as it can be performed on a single slide.
authors.affiliation: Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.
authors.forename: Malini
authors.initials: M
authors.lastname: Srinivasan
authors.forename: Anil V
authors.initials: AV
authors.lastname: Parwani
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D002277:Carcinoma / Q000737:chemistry / Q000175:diagnosis* / Q000473:pathology; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008565:Membrane Proteins / Q000032:analysis*; D060787:Neoplasm Grading; D010414:Pennsylvania; D011237:Predictive Value of Tests; D011471:Prostatic Neoplasms / Q000737:chemistry / Q000175:diagnosis* / Q000473:pathology; D012680:Sensitivity and Specificity; D014157:Transcription Factors / Q000032:analysis*; D025521:Tumor Suppressor Proteins / Q000032:analysis*; D014571:Urologic Neoplasms / Q000737:chemistry / Q000175:diagnosis* / Q000473:pathology; D019459:Urothelium / Q000737:chemistry / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D008565:Membrane Proteins; C115051:TP63 protein, human; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C422655:prostein