Diagnostic and prognostic significance of claudin expression in renal cell carcinomas

Objective: Renal cell carcinomas consist % 2-3 of all cancers and more than % 90 of the renal masses. Eosinophilic and granuler cytoplasmic tumors of kidney are oncocytomas and eosinophilic variants of the cromophobe, papillary and clear cell subtypes of renal cell carcinomas. Currently, there are studies to differentiate these tumors by markers. In our study, we performed claudin 1, 3, 4, 7 and 8 on renal cell carcinoma types and oncocytoma. The results were compared with grade, stage, prognosis and diagnostic impact.Material and Method: Excision materials of 134 renal cell carcinoma cases which were diagnosed at the Pathology Department of Çukurova University Medical Faculty were studied. The material was consisted of 72 clear cell, 26 chromophobe, 24 papillary renal cell carcinoma and 12 oncocytoma cases. Specimens were fixed in % 10 formaldehide solution, parafin embedded and were stained by hematoxylin eosine. Immunohistochemically, Claudin 1, 3, 4, 7 and 8 were evaluated acording to their staining intesity, diffusiveness and location.Results: By Claudin 1; % 73.1 of chromophobe renal cell carcinoma cases were stained membranous and % 91.7 of the oncocytomas were stained cytoplasmically positive. By Claudin 3; % 81.9 of the clear cell renal cell carcinoma were negative, % 100 of oncocytomas were stained cytoplasmically positive. By Claudin 4; % 95.8 of clear cell renal cell carcinoma, % 75 of papillary renal cell carcinoma, % 34.6 of chromophobe renal cell carcinoma were stained negative, % 100 of the oncocytoma cases were cytoplasmically positive. By Claudin 7; % 84.6 of chromophobe renal cell carcinoma were stained membranous positive, % 91.7 of oncocytoma cases were cytoplasmically positive. By Claudin 8; % 73.6 of clear cell renal cell carcinoma and % 44.4 of papillary renal cell carcinoma were negative, % 100 of oncocytomas were cytoplasmically positive. The specifity of cytoplasmic positivity for oncocytoma and membranous positivity for chromophobe renal cell carcinoma was % 91 and the sensitivity was % 92 with claudin 7. Where as the specifity of membranous staining for chromophobe and cytoplasmic positivity for oncocytoma was % 91 and the sensitivity was % 84.Conclusion: As a result, we found out that claudin 1, 7, 8 can be use at the differential diagnosis of oncocytoma and chromophobe renal cell carcinoma, on the other hand claudin 3, 4 can be useful to differentiate oncocytoma from eosinophilic variant of clear cell renal cell carcinoma. Additionally, we also showed the prognostic impact of claudin 1, 3 and 8 especially at the papillary renal cell carcinoma. Our results pointed out that claudins can be used in a panel as a prognostic parameter and diagnostic marker at the differential diagnosis of the renal cell carcinoma types. Further studies with larger series are needed to evaluate their supports at the treatment strategies.Key words: Claudin, chromophobe, oncocytoma, papillary, renal cell carcinoma.