[845] Fluorescent In Situ Hybridization of Clear Cell Renal Cell Carcinoma with Diffuse Cytokeratin 7 Immunoreactivity

H Faraji, EC Belanger, SJ Robertson, BN Nguyen, KT Mai. University of Ottawa, Ottawa General Hospital, Ottawa, Canada

Background: We studied the numeric gain or loss of chromosomes 7, 17, Y and 3p in clear cell renal cell carcinoma (CRCC) with diffuse immunoreactivity for cytokeratin 7 (CK7), which has been recently described.
Design: Thirty diffusely CK7-immunoreactive and predominantly solid CRCC measuring less than 2 cm (small) in diameter and 3 diffusely CK7-immunoreactive and predominantly solid CRCC measuring from 3 to 6 cm (large) were submitted for fluorescent in situ hybridization (FISH).
Results: Architecturally, the carcinoma consisted of small cysts and solid cell nests with tubules/acini with or without a papillary architecture. The nuclei were frequently and characteristically arranged in a row in an apical location of the tubular/cystic/papillary structures. None of the tumors were associated with distant metastasis or local recurrence. FISH demonstrated no numeric change of chromosomes 7/17 or Y. Loss of 3p25/3p14 was observed in focal areas in 12 small CK7-immunoreactive CRCC and in all 3 large CK7-immunoreactive CRCC. The areas in both small and large CK7-immunoreactive CRCC often displayed weak or negative CK7 immunoreactivity.
Conclusions: CRCC characterized by diffuse CK7 positivity represent a subtype of CRCC with characteristic cytohistopathological morphology distinct from conventional CRCC, with an apparently favorable clinical outcome. There was loss of chromosome 3p in focal areas in many tumors. It remains to be investigated if these neoplasms represent an early stage of development of some CRCC.
Category: Genitourinary (including renal tumors)

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 158, Tuesday Morning


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