High‑Grade renal cell carcinoma with somatic BRCA2 mutation and biphasic morphology: an additional case expanding the...

Renal cell carcinoma (RCC) associated with BRCA2 mutation is an extremely rare but increasingly recognized tumor type with characteristic but variable morphological features and aggressive behavior. We report a new case of high‑grade RCC harboring a somatic BRCA2 mutation in a 69‑year‑old male presenting with painless gross hematuria. The tumor exhibited a complex admixture of solid papillary/alveolar, cribriform, and tubulocystic architectures with prominent eosinophilic nucleoli. A biphasic pattern was observed, with central nests of more bland clear cells forming rosette‑like structures around hyaline basement membrane material, a finding reminiscent of TFEB‑altered RCC. Immunohistochemically, the tumor showed a nonspecific immunophenotype with expression of PAX8, CD10, and vimentin, while other RCC‑associated markers were negative. SMARCB1/INI1, SDHB, and FH expression were retained. Targeted next‑generation sequencing confirmed a somatic BRCA2 truncating mutation and absence of alterations in VHL, MET, TSC1/2/MTOR, SDHx, FH, or MiTF genes. A review of all five previously reported BRCA2‑associated RCCs revealed that all six reported cases (including ours) shared certain features: mixed papillary and solid architecture, high‑grade cytology with prominent nucleoli, and absence of other RCC‑defining molecular drivers. Our case not only reinforces the previously reported features but also expands the morphological spectrum of BRCA2‑associated RCC, providing further evidence that this may represent a distinct subtype of RCC.