Cellular mesoblastic nephroma with liver metastasis in a neonate: prenatal and postnatal diffusion-weighted MR imaging

Abstract

Congenital mesoblastic nephroma (CMN) is the most common renal tumor in the first year of life. Here, we present unique findings of cellular variant CMN seen on prenatal and postnatal MRI with diffusion-weighted imaging (DWI).The mass was well-visualized on prenatal MR DWI with diffusion restriction in the solid portions. After excision of the mass, follow-up whole body MRI with DWI helped identify local tumor recurrence with suspicious liver metastasis. This hepatic lesion also showed diffusion restriction.

Keywords: Congenital mesoblastic nephroma; Diffusion-weighted imaging; MRI.

Fig. 1

Cellular mesoblastic nephroma in a female neonate. A-C. Fetal MRI shows huge mass (arrows) occupying left retroperitoneum. Solid portions show intermediate signal intensity on axial T2-weighted image (A) and right kidney (arrowhead) is visible. Solid portion of mass shows true diffusion restriction on diffusion-weighted imaging (B, white arrows) and on apparent diffusion coefficient map (C, black arrows). D. Postnatal, preoperative ultrasonography shows huge solid and cystic mass (arrows) in left abdomen. E. Gross pathology of resected mass is composed of solid and cystic portions. F-I. Whole body MRI during follow-up shows huge cystic recurrent mass (arrows) in left retroperitoneum on T2-weighted image (F) with liver dome mass (arrow), appearing as high signal on T2-weighted image (G) and diffusion restriction on diffusion-weighted imaging (H) and apparent diffusion coefficient map (I).