S3498 Surprising Case of a Pancreatic Mass of Prostate Primary

Introduction: Pancreatic lesions are most commonly due to primary pancreatic malignancy. Metastatic disease to the pancreas is rare, and most commonly from renal cell carcinoma. However, a variety of other cancers may also spread to the pancreas. Here, we report a surprising case of pancreatic metastasis from prostate cancer. Case Description/Methods: Sixty-five-year-old man with chronic tobacco use presented with persistent, acute chest and abdominal pain evaluation following a fall-from-standing motorcycle injury. He was otherwise healthy and denied any constitutional symptoms or family/personal history of cancer. Cross-sectional imaging revealed numerous acute displaced fractures of the right 7th-10th ribs consistent with his fall injury and also incidental findings concerning for underlying metastatic malignancy including an ill-defined hypo-enhancing 1.3 × 1.2 cm mass in the pancreatic head/genu with upstream parenchymal atrophy and ductal dilation, a 1.0 cm mass in the right hepatic lobe, an enlarged and irregular prostate measuring 5.2 × 4.2 cm with posterior mass effect on the rectum and urinary bladder, peri-rectal and pre-sacral lymphadenopathy, and diffuse lytic and sclerotic bone lesions. Labs revealed a cholestatic pattern of elevated liver enzymes, with elevated Alkaline Phosphatase 316 IU/L and mild elevation of AST/ALT, but normal bilirubin levels and without biliary ductal dilation on imaging. He underwent endoscopic ultrasound guided FNB of the pancreatic lesion, which returned as high-grade poorly differentiated adenocarcinoma consistent with a prostatic primary. His PSA was 238 ng/ml, increased from 2.72 ng/ml 10 years prior. His case was discussed at the multi-disciplinary tumor board which recommended systemic chemotherapy and palliative radiation therapy. Discussion: Metastatic involvement of the pancreas is rare, with reports estimating only 2%-5% of pancreas lesions being metastases from other primary cancers. This is significant as the prognosis of pancreatic ductal adenocarcinoma is poor. This case is instead a rare example of prostate adenocarcinoma with metastases to the pancreas. The main site of metastasis for prostatic adenocarcinoma is the bone, with additional spread to the liver and thorax, all seen in this case. This case highlights the importance of an expedited tissue biopsy for diagnosis as primary vs secondary pancreatic tumors can have vastly different treatments and prognoses.