CT and MRI imaging features and long-term follow-up of adult Wilms' tumor

Background: Only few previous case reports have been found focusing on the imaging findings of adult Wilms' tumor (WT). Purpose: To characterize multislice computed tomography (MSCT), magnetic resonance imaging (MRI) characteristics, and follow-up results of adult WT. Material and Methods: Sixteen patients with WT were studied retrospectively. MSCT and MRI were undertaken to investigate the tumor characteristics. Results: Tumors (mean diameter, 13.1 +/- 4.5 cm) exhibited an expansible appearance and disrupted the reniform contour (16/16), cystic components (16/16), curvilinear calcification (1/16), poorly marginated (2/16), hemorrhage (16/16), displacement of renal pelvis or calyx (13/16), and had lymph node or distal metastases (5/16). Attenuation of WT was less or equal compared to renal parenchyma on unenhanced CT (P > 0.05), while tumor enhancement after administration of a contrast agent was lower than that of normal renal parenchyma (P < 0.05). WT was isointense on T1-weighted (T1W) imaging, isointense or hypointense on T2-weighted (T2W) imaging. Tumor enhancement was less than normal renal cortex in all phases (P < 0.05). The number of tumor stages (grades I, II, III, and IV) was two, three, six, and five cases, respectively. Follow-up time was in the range of 19-123 months; six patients died within 3 years, six patients died within 5 years after the initial diagnosis, with the remaining patients still alive. Conclusion: Adult WT tends to be a large tumor, isointense or hypointense on T2W imaging with enhancement less than normal renal parenchyma in all phases. The long-term follow-up results demonstrated the poor prognosis of the tumor.