Details
Renal mass.
This renal neoplasm is composed of multiple dilated cysts, grossly well-circumscribed with fibrous pseudocapsule. Microscopically, the septa between dilated cysts are lined by a single layer of tumor cells with abundant clear cytoplasm and small bland nuclei without prominent nucleoli (WHO/ISUP grade 1 or 2). The tumor cells do not typically show any expansile or solid growth pattern, and they stain strongly with PAX8 and carbonic anhydrase IX – as would typical clear cell RCC.
Similar to clear cell RCC, the presence of VHL mutation and deletion of chromosome 3p have been identified. Prognosis is excellent. The synonymous term multicystic clear cell RCC is no longer recommended.
D/dx: clear cell carcinoma with cystic change, tubulocystic renal cell carcinoma, cystic clear cell papillary renal cell carcinoma.