Diagnosis of renal metanephric adenoma: relevance of immunohistochemistry and biopsy

Most renal tumors of the adult are carcinomas. Their treatment is surgical, consisting of limited excision or nephrectomy. In some instances, biopsy of the tumor can be performed in order to adapt treatment. We report the case of a 45 year-old woman presenting with renal tumor. A biopsy of the mass showed a metanephric adenoma. No surgical excision was performed because of the benignity of this tumor. Here we develop the interest of immunohistochemistry for differential diagnosis of metanephric adenoma and other "basophilic small cell tumors" of the kidney. We also put the stress on the growing role of biopsy of renal tumor allowing optimal treatment.