Diagnostic and surgical challenges of a lymph node metastasis from occult gastric cancer mimicking a pancreatic head tumor: A case report

Pancreatic head tumors are usually regarded as primary pancreatic neoplasms; however, metastatic lymph nodes from gastrointestinal malignancies may occasionally mimic pancreatic tumors and lead to diagnostic and therapeutic challenges, particularly when the primary lesion cannot be identified preoperatively. In the present case report, a 76-year-old man was referred for evaluation of a pancreatic head mass with elevated serum carbohydrate antigen 19-9 levels. Contrast-enhanced computed tomography and positron emission tomography-computed tomography demonstrated a protruding lesion in the pancreatic head and an enlarged infrapyloric lymph node, without evidence of a primary gastrointestinal tumor. Esophagogastroduodenoscopy was unremarkable and primary pancreatic cancer was suspected. Endoscopic ultrasound-guided biopsy of the infrapyloric lymph node revealed adenocarcinoma; however, the primary site could not be determined. Pancreaticoduodenectomy was planned. Intraoperatively, the lesion appeared to represent a bulky metastatic lymph node rather than a primary pancreatic tumor, and distal gastrectomy was additionally performed. Histopathological examination confirmed metastatic lymph node involvement from occult gastric cancer. The patient remains alive without evidence of recurrence 2 years after surgery. In conclusion, occult gastric cancer metastasis can masquerade as a pancreatic head tumor. Awareness of this diagnostic and surgical challenge may facilitate appropriate intraoperative reassessment when pancreatic head lesions are accompanied by suspicious perigastric lymphadenopathy.