A slightly blue, arcuate vessel can be seen on the upper lip mucosa. (from Color Atlas of Oral and Maxillofacial Diseases)
Larger arterial vessels normally are found within the deeper connective tissues. However, occasionally a large branch of an artery will extend close to the mucosal surface without a reduction in its diameter—a vascular anomaly known as a caliber-persistent artery. This lesion is seen most frequently in older adults, suggesting that it may represent an age-related phenomenon related to loss of tone within the surrounding connective tissues. Caliber-persistent arteries almost always occur on the lower or upper labial mucosa; some patients may develop lesions on both lips or bilaterally. The lesion appears as a curvilinear or papular elevation that can appear bluish in color. The artery may become less obvious when the lip is stretched. Pulsation may be noted within the vessel, although it may be difficult to feel this pulse through gloved fingers. The lesion is usually asymptomatic, although overlying mucosal ulceration has been reported in a few examples. Because of its benign nature, no treatment is necessary. However, sometimes a biopsy will be performed because the lesion is mistaken for a mucocele or hemangioma. In such instances, significant bleeding may be encountered.
发生在唇部的Caliber-persistent artery有人译作“唇恒径动脉”，类似的血管病变除了caliber-persistent artery，还有静脉湖（静脉曲张——varicosity or varix）和动静脉畸形，发生于唇部的化脓性肉芽肿内部亦可见到较多毛细血管增生。