[Chromophobe renal cell carcinoma: a clinicopathological study of 16 cases].

Pathological characteristics, patient outcome, and preoperative examinations of 16 cases (4.1%) of chromophobe renal cell carcinoma (RCC) observed among 389 patients with RCC treated at Yokohama City University Hospital and Yokohama City University Medical Center between 1991 and 2004 were analyzed. The age distribution was 16 to 74 years old (average age; 50.9 +/- 17.0). Pathologically, 14 patients had pure chromophobe RCC, and two patients had chromophobe RCC coexisting with aggressive pathological elements, that is, sarcomatoid change in one patient and collecting duct carcinoma in the other. The average tumor size was 7.1 +/- 4.1 cm. On preoperative imaging studies with enhanced computed tomography or angiography, all cases showed a hypovascular pattern. C-reactive protein (CRP) and immunosuppressive acidic protein (IAP) were increased specifically in the two cases coexisting with aggressive pathological elements. Fourteen cases showing pure chromophobe RCC did not metastases on preoperative examination. Thirteen cases were treated by nephrectomy, and another was treated by partial nephrectomy. To date there have been no recurrences during the 6 to 160 months postoperative follow-up. The patient with a mixture of chromophobe RCC and sarcomatoid change (pT3aN0M0) died of multiple lung metastases 18 months after nephrectomy. The patient showing a mixture of chromophobe RCC and collecting duct carcinoma demonstrated metastases to the paraaortic lymph nodes at preoperative examination (pT1bN2M0), and died of multiple lung and bone metastases and carcinomatous peritonitis 8 months after nephrectomy. The patients with pure chromophobe RCC had a favorable prognosis, but those with a mixed type including aggressive elements such as sarcomatoid change or collecting duct carcinoma, showed a poor clinical course. The increase in CRP or IAP could predict poor prognosis in such cases.