An unusual cause of chyluria after radiofrequency ablation of a renal cell carcinoma: a case report

INTRODUCTION This report highlights a rare cause of chyluria occurring after radiofrequency ablation of a renal cell carcinoma. The condition requires a high index of suspicion, as it may not be diagnosed routinely on imaging follow-up after treatment. As chyluria can vary from no symptoms to hypoproteinemia, hypolipidemia and impaired immune function, prompt diagnosis will allow timely management of symptoms. CASE PRESENTATION During a routine renal examination, an otherwise fit and well 79-year-old Caucasian man was found to have a peripherally situated tumor. He underwent renal radiofrequency ablation as primary treatment. Periodic imaging follow-up over two years showed no evidence of residual or recurrent disease within the zonal ablation. The routine imaging protocol at St James's Hospital included upper abdomen only for kidney assessment; pelvic examination was not included. However, our patient underwent a computed tomography scan of his abdomen and pelvis at the request of his local urologist, around two and a half years after the renal radiofrequency ablation. A fat-fluid level was seen within the urinary bladder, consistent with chyluria. As our patient was asymptomatic, he was treated conservatively. CONCLUSION It is important to be aware of chyluria as a possible complication of renal radiofrequency ablation, and to recognize the fat-fluid level sign within the bladder or collecting system on computed tomography scans. As most institutions do not routinely perform computed tomography scans of the pelvis as part of their follow-up protocol after renal radiofrequency ablation, a high index of suspicion is required for diagnosis. Routine urine analysis for fat should be considered, as prompt diagnosis is crucial to guide management for symptomatic patients.