Rhabdomyosarcoma of the kidney

Rhabdomyosarcoma is considered the most common soft tissue sarcoma arising in patients younger than 15 years old, accounting for 5%-10% of childhood solid tumors. Sarcoma of the kidney represents 1% of all primary renal malignancies. Primary renal rhabdomyosarcoma is a very rare entity with limited number of cases reported in the literature. In this paper we present two cases of primary renal rhabdomyosarcoma in pediatric patients. The two tumors involved the renal parenchyma and occurred in 2-year-old girl and 6-year-old boy, respectively. Histopathology examination and immunohistochemistry studies confirm the diagnosis of embryonal rhabdomyosarcoma with pleomorphic component, and pleomorphic rhabdomyosarcoma, respectively. Both cases are treated with chemotherapy and show a good response with no evidence of recurrence or metastasis. The aim of this paper is to expand the differential diagnosis of primary mesenchymal kidney tumors in pediatric age group.