Lechpammer M et al. – Based on distinct expression patterns, claudins 7 and 8 may be useful immunohistochemical markers for separation of chromophobe renal cell carcinomas (RCCs) from oncocytomas, and claudins 3 and 4 may be prognostic indicators in clear cell RCCs Methods
Study of the expression patterns of claudins 1, 3, 4, 7, and 8 in human RCC and oncocytoma
Correlation of expression with pt prognosis
Tissue microarrays created from paraffin-embedded tissue samples from 141 patients with RCCs or oncocytoma: 90 clear cell, 22 papillary, 17 chromophobe RCCs, and 12 oncocytomas
Results
Staining pattern for claudins 3, 4, 7, and 8 was membranous and/or cytoplasmic vs predominantly membranous for claudin 1 in both nonneoplastic renal tissue and tumors
Negative to weak claudin 3 staining predominantly detected in Fuhrman's grade 1 and 2 clear cell RCCs, suggesting upregulation is potentially concomitant with increasing grade of clear cell RCCs
Significant inverse correlation between moderate to strong claudin 3 and 4 expression with overall survival in clear cell RCCs on Kaplan–Meier univariate analysis
Moderate to strong claudin 7 expression was significantly more common in chromophobe RCCs (94%) vs oncocytomas (55%)
Claudin 8 staining was moderate to strong in 92% of oncocytomas, differentiating from papillary (14%) and clear cell RCCs (12%)
Only negative to weak claudin 8 staining was noted in all chromophobe RCCs, vs no claudin 8 negative oncocytomas and 8% with weak staining
