Correlation between preoperative staging computerized tomography and pathological findings after nodal sampling in children with wilms tumor

Purpose: Guidelines for staging Wilms tumor mandate regional lymph node sampling at nephrectomy. However, the usefulness of preoperative computerized tomography in staging lymph nodes has not been rigorously investigated. Thus, we correlated preoperative computerized tomography and pathological lymph node findings to establish a radiological criterion for pathological lymph node enlargement. Materials and Methods: We reviewed the medical records of children with Wilms tumor at our institution who underwent pre-chemotherapy surgery with lymph node sampling and had preoperative computerized tomography with contrast medium available for interpretation. Computerized tomography was independently reviewed by 2 radiologists blinded to the pathological findings. We collected data on the diameter of the largest regional lymph node identified and this measurement was correlated with the pathological results. Results: A total of 52 children (25 male, 27 female) with a median age of 3.1 years (range 0.4 to 9.6) were identified. The median largest regional lymph node diameter was 6 mm (range 2 to 15). Of the children 10 (19.2%) had metastatic involvement of sampled lymph nodes. A radiological cutoff of 7 mm for lymph node positivity corresponded to a negative predictive value of 89.0%, a sensitivity of 70.0% and a specificity of 57.1%. A ROC curve was constructed with these data describing the prognostic ability of the diameter of the largest regional lymph node on preoperative computerized tomography to determine lymph node positivity in Wilms tumor, which revealed an AUC of 0.67 (95% CI 0.48-0.87, p = 0.09). Conclusions: By defining a radiological size cutoff for suspicious lymph nodes, preoperative computerized tomography for staging lymph nodes in Wilms tumor demonstrates potential clinical usefulness through risk stratification for therapy and future study design.