Background: Urothelial carcinoma (UC), previously termed transitional cell carcinoma, is an uncommon but aggressive malignancy arising from the urothelium of the renal pelvis and ureter. It is characterized by a high propensity for multifocality, local invasion, and distant metastasis. Synchronous multicentric involvement extending from the renal pelvis to the ureter and vesicoureteric junction is rare and reflects a pan-urothelial field change, posing diagnostic and therapeutic challenges. Case Presentation: We report the case of a 60-year-old female who presented with intermittent, colicky left loin pain of six months’ duration, without hematuria or constitutional symptoms. Contrast-enhanced computed tomography revealed a large hypoenhancing mass arising from the left renal pelvis with frond-like intraluminal calyceal extensions, severe pelvicalyceal dilatation, marked cortical thinning, and encasement of the left renal artery with renal vein involvement. Tumor extension was noted into the proximal and mid ureter, along with a separate lesion at the left vesicoureteric junction producing an intravesical filling defect. Enlarged left renal hilar lymph nodes and multiple hepatic lesions were identified. FDG PET-CT demonstrated metabolically active disease involving the renal pelvis, ureter, vesicoureteric junction, renal vein, and liver, consistent with multicentric metastatic UC. The patient underwent biopsy and histopathological examination confirmed urothelial cell carcinoma. Conclusion: This case highlights the aggressive behavior and multicentric nature of UC, emphasizing the importance of comprehensive imaging for accurate staging. Recognition of synchronous pan-urothelial involvement is crucial, as it is associated with advanced disease, poorer prognosis, and the need for radical management with close oncologic surveillance.

Keywords:Urothelial carcinoma; Renal pelvis tumor; Multicentric urothelial carcinoma; CT urography; FDG PET-CT