Supernumerary transitional cervicothoracic vertebra and interrupted left subclavian artery reconstituted by a left vertebral arteria lusoria crossing a foramen transversarium.

We report an observation of a right aortic arch with an isolated left subclavian artery (Edwards III-C) occurring in association with a supernumerary transitional cervicothoracic vertebra. As a unique feature, reconstitution of the left subclavian artery involved a left vertebral arteria lusoria, resulting in the formation of a composite anomalous vessel that mimicked an aberrant subclavian artery, followed a retroesophageal course, and passed through the foramen transversarium of the supernumerary vertebra.