Clear cell papillary renal cell carcinoma

Abstract

Clear cell papillary renal cell carcinoma is a newly described variant of renal cell carcinoma (RCC). The International Society of Urological Pathology (ISUP) Vancouver Classification of Renal Neoplasia has recently endorsed it as a distinct epithelial tumor entity and recommended the inclusion of this tumor in the ISUP Vancouver modification of the WHO 2004 histologic classification of RCCs. These tumors were originally described as a distinctive type of RCCs arising in end-stage renal disease; however, tumors with similar features can arise sporadically and have been reported in kidneys not affected by end-stage renal disease. Clear cell papillary RCCs have a distinctive morphology and immunoprofile which will be discussed in this slide seminar with case examples. Tumors with similar morphology and identical immunoprofile but also showing a characteristic smooth muscle stroma have been reported in the literature as renal angiomyodenomatous tumor (RAT). The current perspective is that both clear cell papillary RCC and RAT represent the morphologic spectrum of a single entity. Clear cell papillary RCCs lack the chromosome 3p deletion and VHL gene abnormalities, commonly seen in classic clear cell RCCs. They also lack trisomy of chromosome 7 or loss of Y chromosome, which are cytogenetic changes commonly observed in papillary RCCs. Recently clear cell papillary-like RCCs have been described in VHL patients; however these tumors lack the characteristic immunoprofile of typical clear cell papillary RCCs and frequently demonstrate chromosome 3p deletion. Clear cell papillary RCCs are typically small, biologically indolent tumors. No lymph node or distant metastasis of these tumors has been reported to date in the literature.