Papillary renal cell carcinoma: current and controversial issues.

Area of Science:

• Oncology
• Renal Cell Carcinoma Research
• Molecular Pathology

Background:

• Papillary renal cell carcinoma (pRCC) is the second most common subtype of renal cell carcinoma (RCC), accounting for 15-20% of all cases.
• The traditional classification of pRCC into type 1 and type 2, established 25 years ago, is being challenged by recent discoveries.
• Novel tumor entities and a molecularly defined classification system are emerging for pRCC.

Purpose of the Study:

• To review recent studies on the molecular complexity of pRCC.
• To discuss the evolving differential diagnosis of pRCC in light of new findings.
• To highlight the importance of understanding molecular aberrations for future pRCC classification and treatment.

Main Methods:

• Literature review of recent studies on pRCC.
• Analysis of novel tumor entities described in the 2022 WHO classification.
• Examination of the molecular background of emerging pRCC subtypes.

Main Results:

• New tumor entities like biphasic hyalinizing psammomatous RCC and papillary renal neoplasm with reversed polarity are recognized.
• The 2022 WHO classification provides a new perspective on the molecular basis of pRCC.
• Immune checkpoint inhibitors and tyrosine kinase inhibitors are now standard first-line treatments for advanced pRCC.

Conclusions:

• A deeper understanding of molecular aberrations in new pRCC subtypes is crucial.
• Improved classification of pRCC patients may result from correlating molecular data with new subtypes.
• Potential predictive biomarkers for pRCC subgroups could be identified through further research.