METANEPHRIC ADENOMA OF THE KIDNEY

A case of a rare renal tumor showing characteristic histologic feature s is presented. The patient was a 54 year old female, whose renal tumo r was incidentally detected an abdominal ultrasound (US) examination. Ultrasound, computed tomography and angiography findings were consiste nt with a diagnosis of renal cell carcinoma of the hypovascular type. Left nephrectomy was performed. The tumor, which measured 2.6 x 2.6 x 2.5 cm, was located in the left renal cortex, and had a uniformly whit ish-yellow cut surface and well-defined margin. Histologically, the tu mor was characterized by its monomorphous growth pattern and was compo sed of uniformly small cells arranged in a tubular or rosette-like pat tern. The tumor cells had scant cytoplasm and the nuclei were small, r ound and regular. These histologic features resembled the epithelial e lements of a metanephric hamartoma in the nephroblastomatosis complex in infants. However, there was no mitosis and cellular atypia was mini mal, suggesting benignity. According to these histologic features, the diagnosis of metanephric adenoma was made. Its clinicopathologic feat ures are discussed.