[Renal carcinoma of sarcomatoid chromophobe cells]

Based on the clinicopathological findings of two additional cases of sarcomatoid chromophobe renal cell carcinoma and a review of the literature, we analyzed the prognosis in this and other forms of sarcomatoid carcinoma to determine the differences, if any, and their histopathological basis.

Of 139 cases of renal cell carcinoma that were surgically resected during the period 1977-1999, two were sarcomatoid chromophobe renal cell carcinoma, accounting for 15% of 13 cases of chromophobe cell carcinoma and 18% of 11 cases of sarcomatoid cell carcinoma in the same series.

The first case was a 73-year-old male with a locally advanced, non-metastatic tumor. Palliative resection was performed and the histological analysis showed a predominantly sarcomatoid mass with small epithelial foci with the morphological, histochemical and immunohistochemical characteristics of chromophobe renal cell carcinoma. The patient died 11 months later. The second case was a 70-year-old female who presented with flank and lumbar pain and episodes of gross hematuria. Anatomopathological analysis showed a chromophobe cell carcinoma with sarcomatous foci, stage pT2pN0M0. The patient is disease-free at 46 months' follow-up. Immunohistochemically, in both cases the sarcomatoid component was found to be strongly positive for vimentin and focally for EMA, and negative for actin, desmin and myoblogin; isolated cells were positive for AE1 and AE3 in the second case. The epithelial component was positive for AE3 and EMA, and negative for AE1, vimentine and CD68.

Like our first case, most of the reported cases of sarcomatoid chromophobe renal cell carcinoma show a sarcomatoid mass with foci of carcinoma, and a poor prognosis. In our view, as in all renal cell carcinomas, prognosis depends on tumor grade and stage, which is the highest for sarcomatoid chromophobe renal cell carcinoma. Furthermore, although the epithelial component (chromophobe, chromophilic, clear cells, etc.) may probably have little significance, the influence that the proportion of epithelial and sarcomatoid component might have in these tumors cannot be completely discarded.