Elongation of the anterior tubercle of a cervical vertebral transverse process: an unusual variant.

Elongation of the anterior tubercle of a transverse process of a cervical vertebra is a congenital anomaly that should be considered in a patient demonstrating a bony mass projecting anterior to the vertebral body on a lateral radiograph of the cervical spine. Reported is a case of elongation of the tubercles of the transverse processes of both C5 and C6 with the formation of an articulation. Computed tomography was used to definitively differentiate this variant from a fracture fragment, bone tumor, or osteophyte. This anomaly is probably a form of supernumerary cervical rib developing at a level above the lowest cervical vertebra.