A pulsatile mass is mostly suggestive of a vascular lesion or closely related to blood vessels. Imaging examinations such as angiography and blood flow ultrasound can clearly localize, quantify and qualify the diagnosis, and can provide a detailed understanding of its blood supply and its relationship with the surrounding macrovessels. A pulsatile mass on the clavicle is a clinical manifestation of peripheral aneurysm. Peripheral aneurysm refers to aneurysms occurring in the carotid artery, limb arteries and other arteries of each trunk. Etiology: Etiology and classification are generally divided into two kinds of true aneurysms and pseudoaneurysms: the former is usually caused by atherosclerosis, and its aneurysm wall contains the three-layered structure of the arterial wall, which can be multiple or co-exist with aortic aneurysm; the latter is often secondary to arterial trauma (e.g., knife stab wounds, arterial puncture), and its aneurysm wall is of fibrous tissue, which is mostly solitary. Various infectious factors (e.g., infectious emboli dislodged during bacterial endocarditis), can also destroy the arterial wall, forming the so-called infected aneurysm. Examination: Patients with high aortic aneurysms may present with pulsations at the sternoclavicular joint or a palpable pulsatile mass in the suprasternal fossa. When the aneurysm gradually enlarges into the anterior chest wall and erodes the sternum, it can cause severe pain, and in severe cases, the aneurysm can penetrate the chest wall and appear as a pulsatile mass. Descending aortic hemangiomas may erode the transverse process of the thoracic vertebrae or ribs, or even project out of the back onto the body surface.