Metanephric adenoma treated with laparoscopic nephrectomy: A case report.

Metanephric adenoma is an uncommon benign renal tumor that occurs predominantly in adult females and rarely in children. Its histomorphology resembles that of epithelial Wilms' tumor and papillary renal cell carcinoma. From a diagnostic and therapeutic perspective, recognition of this entity is important as it has a more favorable clinical outcome compared with Wilms' tumor and renal cell carcinoma. Metanephric adenoma should not be treated with nephrectomy if the tumor size is small. However, preoperative diagnosis of this disease is extremely challenging. The present study describes a case of this rare disease, which was treated with laparoscopic nephrectomy. The tumor was not clearly enhanced in the early phase on contrast-enhanced computed tomography imaging. The immunohistochemical analysis revealed positive immunoreactivity for vimentin and Wilms' tumor 1, and partial positivity for cytokeratin (CK) AE1/AE3, CK56, and CK34, consistent with metanephric adenoma. Although metanephric adenoma is difficult to diagnose preoperatively, this rare disease must be considered in order to avoid unnecessary surgical procedures in these patients.