Leiomyoma of the kidney

This is the report of a 27-year old woman with a symptomatic leiomyoma of the left kidney. Symptoms consisted of a mild discomfort at the left flank and a walking difficulty. A left radical nephrectomy was performed. The tumor measured 15 cm in its largest diameter and was composed of elongated cells which demonstrated positive reactivity with anti-desmin and anti-actin antisera and negative reactivity for S-100 protein and cytokeratins. Histologic differential diagnosis is with other spindle cell renal tumors such as leiomyosarcoma, mesoblastic nephroma, angiomyolipoma, fibroma, schwannoma and sarcomatoid renal cell carcinoma.