A Rare Case of TFE3‐Rearranged and SMARCB1‐Mutated Renal Cell Carcinoma: Diagnostic and Therapeutic Complexities

Renal cell carcinoma (RCC) represents the majority of kidney malignancies, with clear cell RCC being the most common subtype. However, recent advances in tumor genomics have refined RCC classification, highlighting rare molecular subtypes such as TFE3-rearranged and SMARCB1-deficient RCCs. These entities pose unique diagnostic and therapeutic challenges due to their aggressive nature and limited treatment data. We present a rare case of metastatic RCC with concurrent TFE3 translocation and SMARCB1 mutation in a 39-year-old patient. The patient underwent multiple systemic therapies, including immune checkpoint inhibitors (ICIs) and tyrosine kinase inhibitors (TKIs), alongside surgical and radiation interventions. Despite disease progression, a combination of lenvatinib and pembrolizumab has shown recent stabilization. This case underscores the importance of genomic profiling in identifying rare RCC subtypes and guiding treatment decisions. Given the aggressive course and lack of established guidelines, further research is needed to optimize therapeutic strategies for these molecularly defined RCC variants.