Renal perineurioma in childhood.

Perineurioma of the kidney in a 7-year-old girl is described. The tumor in the upper pole was discovered during the evaluation of a urinary tract infection. The neoplasm measured 2.6 cm and radiographically it mimicked a nephroblastoma. The diagnosis of perineurioma was confirmed with histologic, immunohistochemical, and ultrastructural studies. These revealed findings typical of perineurioma of other locations. Histopathologically, differential diagnosis may include nephroblastoma, mesoblastic nephroma, neurofibroma, schwannoma, malignant peripheral nerve sheath tumor with perineural cell differentiation, and other benign and malignant mesenchymal tumors with spindle cell pattern. To the best of our knowledge, we report a unique renal perineurioma in a child.