Supplementary Material for: Metastatic involvement of the ureter from recurrent pancreatic cancer in a patient with multiple prior malignancies: a case report

Introduction: Ureteral metastasis is an exceptionally rare manifestation of malignant disease, with pancreatic cancer as the primary source being particularly uncommon. Because ureteral involvement typically reflects advanced systemic disease and is associated with poor prognosis, early and accurate diagnosis is essential for appropriate clinical management. Case Presentation: A 74-year-old man with a history of surgically treated gastric, colorectal, and pancreatic cancers was under routine follow-up after curative resection of pancreatic cancer. Surveillance computed tomography revealed a periureteral mass accompanied by left-sided hydronephrosis. Subsequently, serum tumor marker levels increased, and 18F-fluorodeoxyglucose positron emission tomography/computed tomography demonstrated increased metabolic uptake confined to the periureteral lesion. As imaging findings alone were insufficient to determine the primary origin, surgical resection was performed. Histopathological and immunohistochemical analyses revealed features consistent with pancreaticobiliary adenocarcinoma, confirming periureteral metastasis from recurrent pancreatic cancer. Postoperatively, systemic chemotherapy with gemcitabine plus nab-paclitaxel was initiated. Discussion: Ureteral metastasis is rare, with pancreatic cancer accounting for only a small fraction of reported cases. The ureter is relatively resistant to metastatic spread because it lacks continuous vascular and lymphatic networks; however, metastases may still occur through specific invasion pathways. In patients with a history of multiple malignancies, determining the primary origin of ureteral metastasis is particularly challenging yet critical for selecting appropriate treatment. Although ureteral metastasis generally indicates advanced disease and an unfavorable prognosis, this patient presented with an isolated periureteral lesion without evidence of additional metastatic disease, allowing definitive diagnosis through surgical resection. Conclusion: This case highlights that pancreatic cancer can cause isolated ureteral metastasis even several years after curative surgery. In patients with a history of multiple malignancies, newly identified periureteral lesions should raise suspicion for metastatic disease, and histopathological confirmation is essential to establish the primary origin and guide optimal systemic therapy.