Pancreatic involvement in lung cancer: Imaging findings and diagnostic challenges in two cases

Pancreatic metastases from lung cancer are uncommon and may be difficult to distinguish from primary pancreatic malignancies. We report 2 patients with lung cancer and pancreatic lesions causing biliary obstruction. The first patient was a 58-year-old man with small-cell lung carcinoma and a pancreatic head mass associated with biliary and pancreatic duct dilatation and extensive vascular contact. Endoscopic ultrasound demonstrated a heterogeneous hypoechoic mass, and endoscopic ultrasound-guided tissue acquisition confirmed a pancreatic metastasis from pulmonary small-cell carcinoma. The patient underwent endoscopic biliary drainage followed by cisplatin and etoposide chemotherapy. The second patient was a 61-year-old man with metastatic lung adenocarcinoma and a progressively enlarging pancreatic head lesion. Two endoscopic ultrasound-guided fine-needle aspirations performed 1 month apart were nondiagnostic. The patient subsequently developed obstructive jaundice caused by a severe distal common bile duct stricture. Endoscopic retrograde cholangiopancreatography allowed biliary drainage and biopsy of the infiltrated major papilla. Histological and immunohistochemical findings supported metastatic adenocarcinoma of pulmonary origin involving the major papilla. Although the pancreatic lesion itself was not histologically confirmed as metastatic, the overall clinical and radiological findings were considered suggestive of pancreatic metastatic involvement. These cases illustrate the considerable imaging overlap between pancreatic metastatic involvement and primary pancreatic malignancy. Imaging findings should be interpreted in conjunction with the oncological history and pathological findings. When pancreatic tissue acquisition is inconclusive, biopsy of another accessible involved site may provide diagnostic evidence of metastatic disease.