Exploring the Potential of Immunohistochemistry to Identify Renal Oncocytoma

Abstract

Objective:

To determine the potential for a novel immunohistochemistry panel to accurately distinguish oncocytoma from other renal tumour subtypes.

Material and methods:

Forty renal tumours removed by surgery between 2000 and 2006 in a single tertiary referral centre in the UK were studied retrospectively. Paraffin blocks from 10 each of oncocytoma, papillary RCC, clear cell RCC and chromophobe RCC were examined. The tumours were tested using a panel of antibodies comprising CK7, CK18, CD15, N-cadherin, E-cadherin and EpCAM.

The primary outcome measure was the number of each tumour type staining positively with each marker. The immunohistochemistry marker was considered to be positive if more than 10% of the tumour cells stained positively. No staining or focal staining (<10% of the tumour cells) was considered a negative test.

Results:

CK7, CD15 and EpCAM were able to distinguish between renal oncocytoma and chromophobe RCC: no oncocytoma stained with either CK7 or EpCAM, however 7/10 (70%) stained positive for CD15. Conversely, 8/10 (80%) chromophobe RCC stained positive with CK7 and EpCAM but none stained for CD15.

Conclusions:

In this preliminary study the immunohistochemistry panel shows promise in differentiating between renal oncocytoma and chromophobe RCC. The panel deserves prospective evaluation on needle biopsy specimens.