Renal leiomyoma in a child: a rare renal tumor.

Renal leiomyoma is a rare benign smooth muscle tumor of the kidney. Most cases are reported in adults, with very few cases described in children. We report a case of right renal leiomyoma in a 6-year-old boy which was suspected of being a Wilms tumor. Contrast-enhanced computed tomography could not differentiate leiomyoma in the kidney, and the mass was diagnosed as a Wilms tumor. Right radical nephrectomy was performed. Diagnosis of renal leiomyoma could only be achieved after histopathologic examination and immunohistochemistry. We recommend that total nephrectomy has to be done in most cases of pediatric renal tumors to avoid the risk of malignancy. There may be a role for nephron sparing surgery, provided the tumor is small, and one has a strong suspicion for the lesion being benign.