A Case of Sigmoid Colon Cancer with Patent Foramen Ovale and Left-Sided Inferior Vena Cava Initially Detected during the Workup for Cerebral Infarction

INTRODUCTION: Patent foramen ovale (PFO) is present in approximately 25% of adults, whereas a left-sided inferior vena cava (IVC) is a rare congenital vascular anomaly. Both conditions are associated with thromboembolic risk; however, their coexistence in patients with colorectal cancer has not been reported. We report a rare case of sigmoid colon cancer complicated by PFO and left-sided IVC, initially detected during the diagnostic workup for cerebral infarction.