A case of de novo extra-stent ulceration induced by persistent plaque protrusion after carotid artery stenting with a CASPER stent for a large-volume unstable plaque.

Plaque protrusion (PP) has been identified as a perioperative complication of carotid artery stenosis treated with carotid artery stenting (CAS). The CASPER stent (CS), a dual-layer micromesh stent, may be able to prevent PP. Despite using CS, de novo extra-stent ulceration induced by persistent PP is rare. A 75-year-old male patient, whose superficial temporal artery-middle cerebral artery bypass tended to occlude, underwent CAS using a CS for symptomatic pseudo-occlusive internal carotid artery with a large-volume unstable plaque. This led to de novo extra-stent ulceration induced by persistent PP, resulting in ischemic stroke that necessitated the application of the stent-in-stent technique. There was no recurrence of cerebral infarction postoperatively at 12 months. Here, we present, to the best of our knowledge, the first case of a patient with de novo extra-stent ulceration induced by persistent PP after CAS that led to de novo extra-stent ulceration. The inhibition of intimal formation on the stent surface caused by persistent PP was considered to be the underlying mechanism. The stent-in-stent technique is beneficial even in cases of PP accompanied by de novo extra-stent ulceration.