Wilms tumor (WT) is the most common renal malignancy in children. Children with favorable histology WT achieve survival rates of over 90%. Twelve percent of patients present with metastatic disease, most commonly to the lungs. The presence of a pleural effusion at the time of diagnosis of WT may be noted on staging imaging; however, minimal data exist regarding the significance and prognostic importance of this finding. The objectives of our study are to identify the incidence of pleural effusions in patients with WT, and to determine the potential impact on oncologic outcomes. A multi-institutional retrospective review was performed from January 2009 to December 2019, including children with WT and a pleural effusion on diagnostic imaging treated at Pediatric Surgical Oncology Research Collaborative (PSORC) participating institutions. Of 1259 children with a new WT diagnosis, 94 (7.5%) had a pleural effusion. Patients with a pleural effusion were older than those without (median 4.3 vs 3.5 years; P = .004), and advanced stages were more common (local stage III 85.9% vs 51.9%; P < .0001). Only 14 patients underwent a thoracentesis for fluid evaluation; 3 had cytopathologic evidence of malignant cells. Event-free and overall survival of all children with WT and pleural effusions was 86.2% and 91.5%, respectively. The rate and significance of malignant cells present in pleural fluid is unknown due to low incidence of cytopathologic analysis in our cohort; therefore, the presence of an effusion does not appear to necessitate a change in therapy. Excellent survival can be expected with current stage-specific treatment regimens.What’s new?Some Wilms tumor (WT) patients have fluid around the lungs, or pleural effusion, at diagnosis, but its effect on outcomes is not well known. Here, the authors evaluated data from 1259 children with WT from 21 hospitals in North America. Pleural effusion was present in 7.5% of patients, higher than the previously reported rate of 4.3%, and management was not standardized among different hospitals. The authors also report that patients with pleural effusion were more likely to present with advanced stage tumors and to have their preoperative tumor rupture, but their outcomes were not significantly worse than other patients.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/174970/1/ijc34188_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/174970/2/ijc34188.pd
