Differentiating Chromophobe Renal Cell Carcinoma From Oncocytoma Remains A Diagnostic Dilemma That Hampers The Utility Of Renal Mass Biopsy

Main Category: Urology / Nephrology
Also Included In: Cancer / Oncology
Article Date: 18 Jul 2006 - 2:00 PDT


UroToday.com - The Achilles' heel that continues to plague the utility of renal biopsy in the evaluation of renal masses is the reliable differentiation of chromophobe renal cell carcinoma (malignant) from oncocytoma (benign). The eosinophilic variant of chromophobe RCC is particularly difficult to distinguish from oncocytoma. Hale's colloidal stain has been utilized in the past but remains technically challenging to widely adopt. In this study, the utility of caveolin-1 expression is examined immunohistochemically as a marker of differentiation between these two histologic subtypes. Caveolin-1 expression has previously been demonstrated to be upregulated in a variety of malignancies and is associated with a worse prognosis.

In this study, 21 chromophobe RCC's and 26 oncocytomas were examined for expression of both caveolin-1 and CK7, which has previously been reported to be of benefit in the differentiation of oncocytoma from chromophobe RCC. All of the chromophobe RCC's stained positive for caveolin-1 whereas 23/26 oncocytomas stained negative. In the remaining three oncocytomas, the caveolin-1 staining was seen in less than 20% of the tumor cells examined. Of note, there was strong staining of tumor associated blood vessels in both tumor types. In contrast, CK 7 staining was noted in all of the chromophobe RCC's and 25/26 oncocytomas.

While not "perfect", immunohistochemical staining for caveolin-1 may increase the diagnostic capability of pathologists to distinguish oncocytoma from chromophobe RCC. The hunt for the cancer specific antigen in RCC continues.

By Christopher G. Wood

References:
Garcia E and Li M, Anatomic Pathology 125: 392-398, 2006.

UroToday - the only urology website with original content written by global urology key opinion leaders actively engaged in clinical practice.

To access the latest urology news releases from UroToday, go to:
http://www.urotoday.com

Copyright © 2006 - UroToday

• Additional
• References
• Citations