Pancreatic metastasis from anorectal malignant melanoma.

This report describes a rare case of anorectal malignant melanoma with metastasis to the pancreas, liver, and small bowel. The patient presented with lower gastrointestinal bleeding and an anal mass. Computed tomography (CT) showed a 4.7 × 6.2 cm mass in the lower rectum. The patient underwent surgery and radiotherapy, achieving a two-year recurrence-free period. However, subsequent CT surveillance revealed a 1.6 cm hypo-dense mass at the head of the pancreas and small liver lesions. An endoscopic ultrasound (EUS)-guided fine-needle biopsy of the pancreatic mass was performed, showing a 2.7 × 1.4 cm hypoechoic lesion and pancreatic duct dilation at the pancreatic head region. The pathological diagnosis confirmed metastatic malignant melanoma. She underwent pancreaticoduodenectomy with liver wedge resection. Following surgery, she remained in remission for another two years before developing liver and jejunal metastases, ultimately succumbing to peritoneal carcinomatosis. This case highlights the diagnostic value of EUS in detecting pancreatic metastasis from anorectal melanoma and illustrates the complexities of managing this aggressive disease. The management of pancreatic metastasis from anorectal melanoma requires careful consideration of surgical resection and systemic therapy.