C-Kit-positive metastatic malignant pigmented clear-cell epithelioid tumor arising from the kidney in a child without tuberous sclerosis.

We report the first pediatric case of malignant pigmented epithelioid clear-cell tumor arising from kidney; the lesion occurred in a 12-year-old girl without tuberous sclerosis. The tumor was widely metastatic to the retroperitoneum and chest, and the patient died of the disease 9 months after diagnosis, despite active chemotherapy. Pigmented epithelioid clear-cell tumor of the kidney is a rare variant of epithelioid angiomyolipoma and a member of the family of perivascular epithelioid cell tumors (PEComas). The tumor demonstrated overlapping features between clear-cell sugar tumor and epithelioid variant of angiomyolipoma. Tumor cells were positive for HMB-45 expression, negative for any evidence of muscular differentiation, and contained melanin pigment and premelanosomes in the cytoplasm. Diffuse C-Kit (CD117) positivity was identified throughout the tumor. This is the first report of C-Kit-positive malignant PEComas.