Mesoblastic Nephroma in a 22 Years Old Woman.

Mesoblastic nephroma is an uncommon renal tumor of infancy and rarely occurs in adults. We report a case of mesoblastic nephroma in adult. A 22-year-old woman, who presented with left flank pain, was found to have a left renal mass by abdominal ultrasonography. Computed tomography revealed a heterogeneous tumor. Left radical nephrectomy was performed. The tumor was a creamy white solid mass. Microscopically, the tumor was composed of spindle cell proliferation. Atypia and mitoses were not identified. Among the tumor cells, there were tubular arranged epithelial elements. The patient was free of recurrence 18 months postoperatively. Mesoblastic nephroma is classified as a benign tumor but recurrence and malignant transformation of this tumor have been reported, so regular postoperative follow up is required.