Background & Objective: Renal tumors are a common finding in diagnostic imaging; these lesions usually are solid or cystic, benign or malignant, and the correct diagnosis may be difficult. The current study aims at to determine the diagnostic accuracy of magnetic resonance imaging for the diagnosis of Wilms tumor taking histopathology as gold standard.

Methodology: This cross-sectional study was carried at the Department of Radiology, The Children’s Hospital & Institute of Child Health Lahore over 6 months from March 2019 to September 2019. The study involved 125 children of both genders aged between 2 years to 14 years presenting with a neoplastic mass in the retroperitoneum on ultrasound abdomen during initial workup. These children were assessed on MRI for the diagnosis of Wilms tumor. Later the diagnosis was confirmed on histopathology which was taken as gold standard and the diagnosis of MRI was judged accordingly as true/false and positive/negative. A written informed consent was obtained from every patient.

Results: The mean age of the children was 5.8±3.9 years having a male predominance with male to female ratio of 1.8:1. Wilms tumor was suspected in 13 (10.4%) children on MRI. The diagnosis of Wilms tumor was confirmed in 13 (10.4%) children on histopathology. MRI was found to be 76.9% sensitive, 97.3% specific and 95.2% accurate with positive and negative predictive values of 76.9% and 97.3% respectively.

Conclusion: In the present study, MRI was found to be 95.2% accurate in the differential diagnosis of Wilms tumor in children presenting with retroperitoneal mass which along with its non-invasive and radiation free nature advocates the preferred use of MRI in the diagnostic evaluation of such children in future oncologic practice.

Keywords: Retroperitoneal Tumor, Wilms Tumor, MRI, Diagnostic Accuracy