Composite distal nephron-derived renal cell carcinoma with chromophobe and collecting duct carcinomatous elements

Chromophobe renal cell carcinoma (RCC) and collecting duct carcinoma (CDC) are derived from the collecting duct epithelia, although their morphology, molecular biologic characteristics and clinical behaviors are quite different. Herein is presented a case of RCC possessing the chromophobe RCC and CDC elements occurring in a 64 year-old Japanese woman. The patient was referred to Yokohama City University Hospital with complaints of persistent back pain and fever. Radiologic examinations revealed a left renal tumor, and radical nephrectomy was performed. The patient died with multiple metastases, 8 months after the operation. The resected tumor showed an invasive growth, and its cut surface was heterogenous with hemorrhage and necrosis. Histologically, the tumor was composed of chromophobe elements with dedifferentiation, and CDC elements. The chromophobe and CDC elements had obvious histological transition. Lectin histochemistry and immunohistochemistry confirmed that this tumor was derived from the distal nephron. c-KIT, p53 and Ki67 antigen showed differential localization between the chromophobe and CDC elements, even in the transitional areas. Along with the previous reports, the present case seemed to be composite RCC derived from the collecting duct, which might present clues to elucidate carcinogenesis in the distal nephron.