Post-traumatic pseudoaneurysm of the thyrocervical trunk.

Pseudoaneurysms of the thyrocervical trunk or its branches are extremely rare. They are often the result of a penetrating injury and commonly iatrogenic in origin. Pseudoaneurysm formation following blunt trauma has twice been reported in the English-language literature. We report a case of a 56-year-old man involved in a motor vehicle collision who presented with a slowly growing mass over the course of 4 months. A magnetic resonance (MR) examination was requested to evaluate the cause of this slowly growing mass. Our case is unique in that MR imaging correctly diagnosed the lesion, which was subsequently treated with ultrasound-guided percutaneous thrombin injection. Our case is the only published instance of treatment of a thyrocervical trunk pseudoaneurysm by direct ultrasound-guided percutaneous thrombin injection.