Chromophobe renal cell carcinoma and 'capsulomas' with acquired cystic disease of the kidney in a long-term hemodialysis patient.

Patients receiving long-term hemodialysis tend to develop renal cell carcinoma (RCC). Among such cases, chromophobe RCC and so-called 'capsulomas' are rarely reported. Here, we report a case of a Japanese woman in her early 70s, who developed both renal lesions after 17 years of hemodialysis. The patient received radical nephrectomy for enlarging renal mass. Grossly, the resected kidney showed a dominant tumor and small-sized subcapsular nodules. Histologically, two types of neoplasm, chromophobe RCC and 'capsuloma', existed with acquired cystic disease of the kidney. Chromophobe RCC had eosinophilic cytoplasm with perinuclear halos, and some tumor cells showed oncocytic features. Hale's colloidal iron staining showed a weakly positive cytoplasmic reaction. Immunohistochemistry was diffusely positive for cytokeratin 7, but negative for vimentin in the tumor cells. 'Capsulomas' were multiple subcapsular nodules composed almost entirely of smooth muscle-like cells with immunoreactivity for melanosome-associated antigen detected by HMB-45.