Solid variant of papillary renal cell carcinoma with spindle cell and tubular components.

The solid variant of papillary renal cell carcinoma, when strictly defined as a tumor in which no true papillae can be identified, is extremely rare, with only a few cases reported in the literature. This tumor is characterized histologically by solid sheets of cells without true papillae; nevertheless, immunohistochemical and genetic analysis supports the classification of this tumor as a variant of papillary renal cell carcinoma. We report a case of solid variant of papillary renal cell carcinoma affecting a young man and provide histologic and clinical follow-up data, adding an additional case of this extremely rare pathology to the literature. In addition, we describe the first case, to our knowledge, of a solid variant of papillary renal cell carcinoma to contain a high-grade (sarcomatoid) spindle cell component.