Aggressive renal cell carcinoma with somatic BRCA2 mutation-an emerging entity? A case report with literature review.

Role of BRCA2 gene mutation in renal tumorigenesis remains largely unclear. There are only two case reports of renal cell carcinoma (RCC) with BRCA2 mutation, both of which showed a high-grade RCC with various architectural patterns including tubulopapillary and solid. The tumor cells were described as having eosinophilic cytoplasm and prominent nucleoli. The current study describes another case of high-grade RCC with somatic BRCA2 mutation with various architectural patterns and cells with eosinophilic cytoplasm and prominent nucleoli. Immunohistochemical staining showed co-expression of PAX8, CAIX, CD10, CK7, CK20, and P504S. This unusual co-expression of the commonly used IHC stains during the workup of RCC could serve as a potential diagnostic pitfall. Although very rare, it is important for pathologists to be aware of this form of RCC due to its aggressive clinical behavior, possibility of a germline mutation, and current therapeutic options for tumors with BRCA2 mutation.