title: Oncocytoma can be differentiated from its renal cell carcinoma mimics by a panel of markers: an automated tissue microarray study.
abstract: BACKGROUND
  Differentiating oncocytoma from its renal cell carcinoma (RCC) mimics, particularly chromophobe RCC, can be difficult, especially when limited tissue is available for evaluation. This study presents a panel of markers that are readily available, easy to use, and useful for differential diagnoses of renal tumors.
  
  
  METHODS
  A renal cell neoplasm tissue microarray was constructed including oncocytoma (n=30), chromophobe RCC (n=18), conventional RCC (n=64), papillary RCC (n=50), and benign renal tissues (n=31). CK7, CD10, epithelial membrane antigen, renal cell carcinoma marker (RCCma), vimentin, and endogenous avidin-binding activity (EABA) were studied. An Automated Cellular Imaging System, was used to quantify the staining intensity.
  
  
  RESULTS
  EABA was positive in 97% of oncocytoma, 26% of conventional RCC and 35% of papillary RCC with granular/eosinophilic (G/E) features and 6% of chromophobe RCC. EABA was negative in RCC without G/E features. Vimentin and RCCma were positive in most RCC with G/E features (conventional, 78% and 71%; and papillary, 85% and 76%, respectively), and negative in oncocytoma. Vimentin was also negative in chromophobe RCC. CK7 was positive in up to 81% of papillary RCC and 63% of chromophobe RCC, and essentially negative in conventional RCC and oncocytoma.
  
  
  CONCLUSIONS
  EABA is an excellent marker for oncocytoma, which can be useful in differentiating oncocytoma from chromophobe RCC. A panel of EABA, vimentin, and RCCma markers can be useful in discerning oncocytoma from RCC with G/E features. Vimentin can be useful in discriminating chromophobe RCC from papillary or conventional RCCs.
authors.affiliation: Immunohistochemistry Laboratory, Department of Pathology and Laboratory Medicine, University of Wisconsin, 2500 Overlook Terrace, Madison WI 53792, USA. whuang@uwhealth.org
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kanehira
authors.forename: Sally
authors.initials: S
authors.lastname: Drew
authors.forename: Thomas
authors.initials: T
authors.lastname: Pier