[913] Fluorescent In Situ Hybridization Study of Non-Papillary Oncocytic/Eosinophilic Renal Cell Carcinoma

M Marinescu, I Ahmed, EC Belanger, SJ Robertson, BN Nguyen, KT Mai. The Ottawa Hospital, Ottawa, ON, Canada; University of Ottawa, Ottawa, ON, Canada

Background: Chromophil (papillary) renal cell carcinoma (PRCC) and clear cell renal cell carcinoma (CRCC) can display extensive areas with oncocytic/eosinophilic changes and may be associated with either minimal or no papillary architecture. These non-papillary oncocytic/eosinophilic renal cell carcinomas (RCC) often mimic renal oncocytoma (RO) and are an uncommon variant of RCC.
Design: Nine cases of non-papillary oncocytic/eosinophilic RCC were retrieved from the files at our institution. We investigated numeric changes of chromosomes 7,17 and Y and loss of the small arm of chromosome 3 using the fluorescent in situ hybridization (FISH) technique.
Results: The tumors displayed an immunoprofile of CRCC or PRCC: RCC (+)/CD117 (-) and variable reactivity for CK7 and AMACR in 7 cases. In addition, there were 2 cases which were previously reported as malignant renal oncocytoma (RO) with an immunoprofile of RCC(-)/CD117(+), marked cytologic atypia and lymph node metastasis. FISH studies showed trisomies 7/17 with or without loss of Y in five tumors. Loss of loci 3p25 and 3p14 were identified in another 2 cases. The remaining 2 tumors with features of RO showed no evidence of numeric changes for chromosomes 7, 17 and Y or loss of loci 3p25 or 3p14.
Conclusions: In this uncommon variant of RCC, FISH for chromosomes 7, 17, Y and 3p lend more support to the role of immunostaining in distinguishing RO and chromophobe RCC from the non-chromophobe RCC. FISH for chromosomes 7, 17, Y and loci 3p25 and 3p14, and not immunostaining for AMCR or CK7, is helpful in distinguishing CRCC from PRCC.
Category: Genitourinary (including renal tumors)

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 137, Tuesday Morning

 

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