S3252 Ghosts of Nephrectomies Past: Renal Cell Carcinoma's Pancreatic Plot Twist

Introduction: Renal cell carcinoma (RCC) is notorious for its potential to metastasize, particularly to the lungs, bones, and liver although pancreatic involvement is relatively rare, RCC remains a common cause of pancreatic metastasis. Imaging characteristics of RCC metastasis to the pancreas include hypervascular metastatic foci that are well defined with discrete margins. We present a case of a patient with a history of RCC who was found to have pancreatic metastasis with diffuse involvement of the pancreas. Case Description/Methods: A 69-year-old woman with a history of RCC status post left nephrectomy in 2007 presented to clinic with a 1-week history of a “pulsatile abdomen”. Computed tomography imaging revealed a diffusely infiltrative hyperenhancing pancreatic mass suspicious for a neuroendocrine tumor (NET). She subsequently underwent endoscopic ultrasound with biopsy, and pathology confirmed metastatic RCC to the pancreas. Positron emission tomography scan showed a large infiltrative mass involving the pancreatic head, body, and most of the tail, with likely invasion of the portal vein and superior mesenteric vein. A left upper lobe lung nodule was also noted, concerning for metastasis. The patient was started on palliative treatment with pembrolizumab and axitinib. Discussion: RCC is one of the most common primary tumors to metastasize to the pancreas even decades after nephrectomy. Pancreatic metastases from RCC typically present as hypervascular lesions with discrete borders on imaging. However, differentiating RCC metastases from neuroendocrine tumors (NETs) from imaging alone remains challenging, as both exhibit similar vascular patterns. RCC has distinguishing features, such as pancreatic and biliary ductal invasion causing jaundice – less common in NETs – and absence of hormone-related symptoms seen in functional NETs. Ultimately, histologic confirmation via endoscopic ultrasound-guided biopsy is essential for definitive diagnosis. Awareness of a prior RCC diagnosis is critical and any hypervascular pancreatic lesion in such patients should prompt strong suspicion for metastatic disease. Notably, when confined to the pancreas, RCC metastases carry a more favorable prognosis.