Aggressive variants of chromophobe renal cell carcinoma

BACKGROUND Chromophobe renal cell carcinoma (RCC) is a distinctive subtype of RCC with a more favorable prognosis than clear cell RCC. We describe the pathologic features of 23 solitary cases and 2 cases with coexistent papillary RCCs, 7 of which developed metastases. METHODS Cases were retrieved from the pathology files of our institutions. Clinical follow‐up was obtained from the medical records. DNA analysis was performed on Feulgen‐stained slides using image analysis. RESULTS Twenty‐five cases were identified. All cases had characteristic pathologic features, including diffuse cytoplasmic reactivity for Hale's colloidal iron. DNA ploidy analysis of ten cases revealed a diploid pattern in five, a hyperdiploid pattern in four, and a hypodiploid pattern in one. Follow‐up was available for 20 cases, and metastases developed in 7 (from 4 to 120 months after surgery). In 5 of these cases, the tumors were solitary and more than 8 cm in greatest dimension and metastases developed in the liver. In both cases with papillary RCCs in the same kidney, metastases developed in the lung, although which tumor metastasized is unknown. CONCLUSIONS Despite the overall favorable prognosis for chromophobe RCC, large tumors and those with coexistent papillary RCCs may produce in metastases. Cancer 1996;78:1756‐61.