Left superior vena cava: a pitfall in computed tomographic diagnosis with surgical implications. We report 2 cases in which computed tomography of the mediastinum demonstrated an abnormality originally misinterpreted as lymphadenopathy but subsequently shown to represent a left superior vena cava. Misinterpretation may result in errors in optimum treatment and may complicate surgical exploration of the mediastinum. These 2 cases are presented to remind radiologists and surgeons of the possibility of this unusual anatomy. 