Tumors of the kidney account for about 3% of adult malignancies, with an incidence of approximately 36 000 new cases/year in the United States. The first classification of renal tumors was proposed by Konig in 1826. This classification was made on the basis of gross morphologic characteristics. Extensive study of renal neoplasms in the last couple of decades has led to a standardized nomenclature by the European and American authorities.
The 2004 WHO classification, which includes nearly 50 distinct entities, is based on a combination of immunohistochemistry, histology, and clinical and genetic features that are widely accepted and relatively reproducible. Several large series have shown this classification to have prognostic significance and that it is
relevant to diagnosis by fine needle aspiration techniques. It is anticipated this current classification system will be reassessed in 5 years
MOLECULAR DIAGNOSTIC TECHNIQUES IN RENAL NEOPLASMS
relevant to diagnosis by fine needle aspiration techniques. It is anticipated this current classification system will be reassessed in 5 years
MOLECULAR DIAGNOSTIC TECHNIQUES IN RENAL NEOPLASMS
The application of molecular and cytogenetic techniques has resulted in improved understanding of these tumors. Routine use of these techniques for diagnosis is cumber some, although they serve as useful adjuncts in selected cases. In the forefront among these technologies are comparative genomic hybridization (CGH), fluorescent in situ hybridization (FISH), allelic loss analysis, classical cytogenetics, and karyotyping. The von Hippel-Lindau tumor suppressor gene resides in the short arm of chromosome and is commonly inactivated by gene mutation or promoter hypermethylation in sporadic clear cell RCC.
It is also the causative gene for the von Hippel-Lindau syndrome.Papillary RCC, chromophobic RCC, carcinoma of the collecting ducts of Bellini, metanephric adenomas, and renal oncocytomas have also exhibited characteristic chromosomal anomalies.
Recently, RCC associated with chromosomal translocation involving TFE3 gene on Xp11.2 has been described as a distinct clinicopathological entity. Differentiating the various histological subtypes of renal tumors is crucial, since they differ in their prognosis and therapeutic response to treatment. Definitive diagnosis based on H&E morphology is possible in the majority of cases. In the minority circumstances where distinction becomes difficult, immunohistochemistry and other molecular techniques are being increasingly relied upon to make the distinction.
Renal cell carcinoma marker (RCC Ma) is a monoclonal antibody against the proximal tubular brush border antigen, which is relatively specific for renal neoplasms that originate from the proximal renal tubules including clear and papillary RCC, despite a rather low sensitivity.The anti body is positive in nearly 80% of clear cell and papillary RCC, is variably expressed in chromophobe RCC, and is absent in oncocytomas and CDCs. CD10 is another marker that helps in the differential diagnosis, by being expressed in clear cell and papillary RCC, and absent in chromophobe RCC and oncocytomas.
Vimentin is variably expressed in clear cell and papillary RCC and is absent in chromophobe RCC and oncocytomas. Cytokeratins represent a widely used diagnostic immunohistochemical marker in differentiating renal tumors. Cytokeratin 7 (CK7) is strongly positive in most chromophobe RCC, absent in clear cell RCC, and variably expressed in oncocytomas. Routine metaphase cytogenetics, performed on cultured tumor cells, has been used to identify cytogenetic changes associated with each RCC histological subtypes. Using specific probe sets, FISH can be used to identify those RCC with characteristic chromosomal alterations
It is also the causative gene for the von Hippel-Lindau syndrome.Papillary RCC, chromophobic RCC, carcinoma of the collecting ducts of Bellini, metanephric adenomas, and renal oncocytomas have also exhibited characteristic chromosomal anomalies.
Recently, RCC associated with chromosomal translocation involving TFE3 gene on Xp11.2 has been described as a distinct clinicopathological entity. Differentiating the various histological subtypes of renal tumors is crucial, since they differ in their prognosis and therapeutic response to treatment. Definitive diagnosis based on H&E morphology is possible in the majority of cases. In the minority circumstances where distinction becomes difficult, immunohistochemistry and other molecular techniques are being increasingly relied upon to make the distinction.
Renal cell carcinoma marker (RCC Ma) is a monoclonal antibody against the proximal tubular brush border antigen, which is relatively specific for renal neoplasms that originate from the proximal renal tubules including clear and papillary RCC, despite a rather low sensitivity.The anti body is positive in nearly 80% of clear cell and papillary RCC, is variably expressed in chromophobe RCC, and is absent in oncocytomas and CDCs. CD10 is another marker that helps in the differential diagnosis, by being expressed in clear cell and papillary RCC, and absent in chromophobe RCC and oncocytomas.
Vimentin is variably expressed in clear cell and papillary RCC and is absent in chromophobe RCC and oncocytomas. Cytokeratins represent a widely used diagnostic immunohistochemical marker in differentiating renal tumors. Cytokeratin 7 (CK7) is strongly positive in most chromophobe RCC, absent in clear cell RCC, and variably expressed in oncocytomas. Routine metaphase cytogenetics, performed on cultured tumor cells, has been used to identify cytogenetic changes associated with each RCC histological subtypes. Using specific probe sets, FISH can be used to identify those RCC with characteristic chromosomal alterations