Absence of the superior vena cava (SVC) is a rare variety of vascular anomaly. The purpose of this report is to describe the computed tomography (CT) findings of the partial absence of the SVC without persistent left SVC in a patient with no evidence of congenital cardiovascular disease and no prior history of central venous instrumentation. A 77-year-old woman with a history of colon cancer underwent thoracoabdominal CT imaging because of abdominal pain of uncertain cause. No tumor recurrence was observed. A complicated"investigation" confirmed a thymoid cancer surgery back in 1976, which was accompanied by resection of the SVC and the left brachiocephalic vein because of their invasion. Owing to the absence of the SVC and bilateral brachiocephalic veins, caval hypertension developed in the patient, resulting in the dilation of cavo-caval anastomoses. In addition, new anastomoses were opened. The clinical significance and possible embryogenesis of this anomaly are discussed. The extremely rare condition of the partial absence of the SVC appeared with subcutaneous dilated, tortuous collaterals in an asymptomatic adult patient. This anomaly is becoming clinically more relevant with the increasing use of minimally invasive vascular surgery.