Retroperitoneal malignant schwannoma in a child.

Retroperitoneal malignant schwannomas are extremely rare. Only a few cases have been reported, only one of which occurred in a child. We herein report a case of retroperitoneal malignant schwannoma in a 2-year-old boy who presented with a painless mass in the right lumbar region. The mass had gradually enlarged during a 1-year period, and it was about the size of the patient's fist at the time of consultation. Whole-abdomen computed tomography revealed a space-occupying lesion in the retroperitoneum infiltrating from the L1 to L4 spinal canal. A preoperative diagnosis of a retroperitoneal tumor was made, and complete tumorectomy was performed. Postoperative pathological examination showed a malignant schwannoma. The tumor recurred 1 month after the first operation, and a second complete excision was carried out; the postoperative pathologic examination findings were similar to the previous findings. The patient recovered well and continued to undergo close follow-up.