In 2013, a 76-year-old male with a cardiac pacemaker was diagnosed with adenosquamous carcinoma of the duodenum. Subsequently, a pancreatoduodenectomy and lymph node dissection were performed, and 12 cycles of adjuvant chemotherapy (modified FOLFOX6 regimen), which consisted of fluorouracil, leucovorin and oxaliplatin, were administered via a central venous catheter. At 5 months after the completion of adjuvant chemotherapy, the patient experienced the sudden onset of severe pain at the back right of the ear, edema of the right side of the face and right jugular vein dilatation. Computed tomography (CT) revealed filling defects in the superior vena cava (SVC) and right brachiocephalic vein, indicating catheter-induced venous thrombosis. Although the catheter was removed and anti-coagulation therapy, aspiration of the thrombosis and ballooning dilatation were performed immediately, the patient's symptoms were not ameliorated. Notably, histological examination following thrombus aspiration revealed metastatic cancer cells, and fluorodeoxyglucose-positron emission tomography/CT identified metabolically active nodules in the SVC at locations consistent with the initial duodenal tumors detected by CT and in the first thoracic vertebrae. The tumor thrombus rapidly increased in size and resulted in worsening dyspnea. Subsequently, radiotherapy was performed, followed by chemotherapy, which relieved the systemic symptoms and suppressed the tumor growth. Adenosquamous carcinoma of the duodenum is extremely rare, and to the best of our knowledge, intraluminal SVC metastasis as a result of adenosquamous carcinoma of the duodenum has not been reported previously. The placement of a cardiac pacemaker, central venous catheter and tumor cells possessing high metastatic potential are hypothesized to have contributed to this rare case of metastasis.
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