Arka Publishing Company Canon Journal of Medicine 2676-5446 Articles in Press 2026 01 05 Clear Cell Renal Cell Carcinoma with A Tumor Thrombus in the Proximal Ureter: A Case Report 238249 10.30477/cjm.2025.533912.1107 EN Hourieh Soleimani Department of Radiology, Faculty of medicine, Mashhad University of Medical Sciences, Mashhad, Iran 0009-0009-7621-4826 Ehsan Hassannezhad Department of Radiology, School of Medicine, Birjand University of Medical Sciences, Birjand, Iran. 0000-0001-9395-4134 Asma Payandeh Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. 0009-0003-0159-7144 Neda Karimabadi Department of Radiology, Faculty of medicine, Mashhad University of Medical Sciences, Mashhad, Iran 0009-0005-6963-7856 Journal Article 2025 07 11 Background: Renal cell carcinoma (RCC) holds the distinction of being the most prevalent cancer of the kidney in adults. Although invasion of surrounding tissue is a common phenomenon in RCC, the spread within the lumen of the collecting system and the ureters is rarely encountered. It may be essential to consider including urinary tract extension in the TNM staging.<br>Case presentation: We present the case of a 57 years old male, with no smoking history and no previous medical conditions, presenting with painless gross hematuria. The patient's CT scan revealed a heterogeneous mass in the left kidney with central necrotic areas. The tumor was found to have spread to the left pelvis and ureter, reaching a distance of 7.5 cm from the ureteropelvic junction. No evidence of left renal vein and IVC involvement was found. Later on, he underwent a radical nephrectomy. An atypical pattern of RCC dissemination was observed, with a tumor protrusion into the renal sinus fat, renal pelvis, and a tumor thrombus extending to the ureter. The histological examination showed a grade 4 clear cell renal cell carcinoma with 10% sarcomatoid features.<br>Conclusion: It may be of significance to consider the inclusion of urinary tract extension in RCC when determining the TNM staging.