[Multilocular cystic renal cell carcinoma: a report of two cases].

Two cases of multilocular cystic renal cell carcinomas in a 48-year-old man and in a 41-year-old woman are reported. Radical nephrectomy was performed in both cases. Both histologic diagnoses were multilocular cystic renal cell carcinoma, clear cell subtype, grade 1. We had some difficulty in diagnosing the latter case with multilocular cystic mass which had smooth, glistening lining and contained clear-yellow fluid. Microscopical examination of the permanent sections revealed that the cysts were lined by a cuboidal or flattened epithelium, but no tumor cells. However, laminar growth of renal cell carcinoma of the clear cell type was present in several areas in the septa, and a few residual tumor cells were found in the hyalinized septa. When renal cell carcinoma is present in only a part of the multilocular cystic renal mass, it should be diagnosed as multilocular cystic renal cell carcinoma. The literature was surveyed.