CT features of metanephric adenoma: a case report and review of the literature

Abstract

Metanephric adenoma (MA) is an extremely rare, benign neoplasm of the kidney. Ultrasound and computed tomography (CT) features of a case of MA in a 49-year-old woman were presented in this paper to enrich imaging manifestations of this rare entity. At plane CT, a solid mass with calcification spots was noted. After iv contrast agency, the mass showed slight irregular peripheral enhancement in the corticomedullary phase, which was obviously lower than surrounding renal cortex. Slowly filling-in was noticed in the nephrographic phase with irregular necrosis.

Keywords: Kidney; computed tomography (CT); metanephric adenoma (MA).

Figure 1

Ultrasound and CT findings of a metanephral adenoma in a 49-year-old woman. Pathological images. (A) Longitudinal scan shows a hypoechoic mass in the superior pole of the left kidney with a clear margin and protruding out of the kidney outline (arrow and cross marks); (B) color Doppler flow imaging in longitudinal scan shows a little blood flow signal in the surrounding and the inner of the mass; (C) unenhanced transverse CT image shows a well-demarcated mass in the superior pole of the left kidney (long arrow) and small spot-like calcification (short arrow) in the mass; (D) transverse CT image in the corticomedullary phase shows slight peripheral enhancement (arrows) of the mass; (E) transverse CT image in the nepherography phase shows the peripheral enhancement increasing in degree and areas with irregular necrosis (star) and well-defined margin (arrows); (F) the cut-surface of the mass (arrows) is in a mixture color of yellowish-grey and tan pink with a well-circumscribed border (short arrows) and irregular necrosis (stars); (G) photomicrograph of histological specimen (hematoxylin-eosin stain, original magnification ×100) shows epithelial cells of the tumor with small, uniform, round nuclei and scant cytoplasm. No karyokinesis was observed.