Utility of cytokeratin 7 for distinguishing chromophobe renal cell carcinoma from renal oncocytoma.
OBJECTIVE
Chromophobe renal cell carcinoma is a relatively uncommon variant of renal carcinoma described in 1985. The main differential diagnosis is renal oncocytoma. Hale's colloidal iron staining is a powerful adjunct to morphological interpretation but it is not specific and is sometimes difficult to interpret. We studied the immunohistochemical expression of cytokeratin 7 to determine its value in distinguishing chromophobe renal cell carcinoma from renal oncocytoma.


METHODS
Immunostaining was performed on paraffin-embedded tumor tissue of 6 chromophobe renal cell carcinomas and 11 oncocytomas with an antibody to cytokeratin 7 (clone OV-TL 12/30, Dako, France) using a streptavidin-biotin method.


RESULTS
All chromophobe renal cell carcinomas showed strong cytoplasmic staining with peripheral cell accentuation. In contrast, 8 of 11 oncocytomas were entirely negative and 3 showed only weak and focal staining in less than 5% of the tumor cells.


CONCLUSIONS
Immunohistochemical staining for cytokeratin 7 may be useful for the differential diagnosis of renal oncocytomas and chromophobe renal cell carcinomas when Hale's colloidal iron staining is uncertain.
Leroy
X
X
Department of Pathology, CHRU, Lille, France. bgosselin@chru-lille.fr
Moukassa
D
D
Copin
M C
MC
Saint
F
F
Mazeman
E
E
Gosselin
B
B
D000230:Adenocarcinoma / Q000473:pathology* / Q000601:surgery; D018249:Adenoma, Oxyphilic / Q000473:pathology* / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001707:Biopsy, Needle; D002292:Carcinoma, Renal Cell / Q000473:pathology* / Q000601:surgery; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D053552:Keratin-7; D007633:Keratins; D007680:Kidney Neoplasms / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity
C507497:KRT7 protein, human; D053552:Keratin-7; D007633:Keratins