Renal neoplasms make up a unique spectrum of tumors with a broad array of molecular genetic alterations and light microscopic morphologic features. A tremendous amount of insight has been gained into their pathogenesis via the study of the multiple inherited renal neoplasia predisposition syndromes. However, the molecular genetic alterations in many tumors remain somewhat mysterious despite relatively well-characterized clinical and histopathologic characteristics. Key molecular genetic features in the most common renal neoplasms include frequent alterations of chromosome 3p in clear cell carcinoma, including abnormalities of the VHL gene, gains of chromosomes 7 and 17 in papillary carcinoma, multiple complex losses in chromophobe carcinoma, and a normal karyotype or loss of chromosome 1 in oncocytoma. However, alterations of a number of other genes and chromosomal loci are also seen in these tumors, suggesting that a complex and incompletely understood interaction of multiple molecular genetic factors is involved in their pathogenesis. Likewise, pathways leading to the development of the other more rare tumors discussed in this chapter are not fully known. In recent years, the application of molecular techniques has led to increased discrimination of morphologically similar entities, and new diagnostic categories have been established based on molecular genetic findings. Applications of molecular studies in selecting targeted therapy will likely also continue to expand.
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