Squamous differentiation in a sarcomatoid chromophobe renal cell carcinoma: an unusual case report with review of the literature.

We describe an extremely rare occurrence of a squamous differentiation in a sarcomatoid chromophobe renal cell carcinoma in a 45-year-old woman with nodal and lung metastasis at presentation. The tumor on histology showed all 3 components intimately admixed with each other, which to the best of our knowledge is the first such case to be reported in the literature. The renal pelvis was smooth walled and uninvolved. Kidney-specific cadherin was positive in the chromophobe renal cell carcinoma areas and negative in the sarcomatoid and squamous areas.