Papillary renal cell carcinoma: what is missing in research? A case report and a review of literature.

The incidence of renal cell carcinomas in adults ranges has been increasing over the past decades in both men and women. Once the incidence was 2.9%, now is reported to have increased to 3%-5% with male predominance according to the most recent reports of cancer statistics. The disease typically describes a group of different histopathological subtypes; the most common is clear cell carcinoma which accounts for 70%-80% of the diagnosed cases, while papillary renal cell carcinoma and chromophobe types represent 20% and 5%, respectively. In 1996, the renal cell carcinomas Heidelberg classification was introduced by Delahunt et al. It divides renal cell tumors into benign and malignant parenchymal neoplasms, excluding Wilm's tumor and secondary metastases and limiting each subcategory to the most commonly documented genetic abnormalities, if applicable. In this report, we discuss a case of metastatic type I papillary renal cell carcinoma treated with the anti-vascular endothelial growth factor receptor sunitinib and showing marked long-term clinical response. Through this case, we highlight the importance of re-classifying papillary renal cell carcinoma subtypes to prioritize the clinical management of these cases.