A Case of the Left-sided Inferior Vena Cava with the Single Column Type of Azygos Venous System

A rare anomaly, in which the left-sided inferior vena cava was present, accompanied by the single column type of azygos venous system, was found in an 86-year-old Japanese female among cadavers for student dissection. The vein in this case appeared to be represented as a persistence of the left postrenal segment of the fetal inferior venae cavae, without any visceral transposition. Accordingly, this case may belong to type A-II-b-2 of Edwards'classification (1951), type C of Reis et al. (1959), I-type C of Chuang et al. (1974), type III of Takemoto et al. (1978), and type II of Yoshida et al. (1981), of variations of the inferior vena cava. Since both the hemiazygos and the accessory hemiazygos veins were iacking in the azygos venous system, this pattern belongs to the single column type of Seib (1934).