The Tumor Entity Denominated “clear cell-papillary renal cell carcinoma” According to the WHO 2016 new Classification, have the Clinical Characters of a Renal Cell Adenoma as does Harbor a Benign Outcome

The new WHO 2016 classification of renal neoplasia encounters the new entity called “clear cell papillary renal cell carcinoma” (ccpRCC). The ccpRCC has been long included as a subtype of clear cell RCC histotype and it actually ranges from 2 to 9% in different routinely available cohort of renal carcinomas. Of important note, ccpRCC does not show any recurrences or metastases or lymph-node invasion and the outcome is always good. We reviewed twenty-four publications with available follow-up for patients (no. 362) affected by clear cell papillary RCCs/renal adenomatoid tumours and notably ccpRCC harbors an indolent clinical behavior after a mean of 38 months (3,5 years) of follow-up. This paper reviews the histological, molecular and clinical features characterizing ccpRCC, with the goal of focusing the knowledge of the benign fashion of this new tumour entity, supporting the idea of a new renal cell adenoma recruited morphologically from ex conventional clear cell RCC tumours.