Pigmented perivascular epithelioid cell tumor of the kidney.

A case of pigmented perivascular epithelioid cell tumor of the kidney in a 57-year-old woman with a clinically indicated tuberous sclerosis is presented. The lesion was a 3.0-cm, well-demarcated, black-colored mass. The tumor was histologically characterized by an epithelioid arrangement of round to polygonal cells with round nuclei and clear cytoplasm containing abundant melanin. Tumor cells showed mild atypia and low mitotic activity. A spindle cell proliferation was focally observed. There were no adipose elements or thick-walled vascular vessels. The stroma demonstrated intervening, thin, fibrovascular septa. Immunohistochemically, the tumor cells were strongly positive for HMB-45 but negative for epithelial and muscle markers, vimentin, and S100 protein. The patient had no evidence of disease 3 months after surgery. Pathologists and clinicians should know about the existence of pigmented perivascular epithelioid cell tumor of the kidney. This type of tumor should be differentiated from clear cell renal cell carcinoma or malignant melanoma.