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.