Pathological analysis of a case with peri-stent contrast staining after BMS implantation.

A 68-year-old female underwent bare-metal stent (BMS) implantation in the right coronary artery (RCA) for ST-segment elevation myocardial infarction. Recurrent refractory restenosis with peri-stent contrast staining (PSS) formation was observed in the stented lesion at follow-up angiography at 7, 11, and 14 months after the index stent implantation. After 2 repeated interventions, this patient was referred to coronary artery bypass grafting due to occlusion of RCA and progression of proximal left anterior descending coronary artery lesion at 15 months after stent implantation. Pathologic examination of the surgically resected specimen of stented RCA segment revealed total occlusion with dense fibrous collagenous tissue and significant inflammatory cell infiltration including scattered eosinophils. Extensive loss of medial smooth muscle layer was observed in the vessel wall, which was likely to be the cause of PSS. In the course of treatment, this patient was found to have chromium allergy with positive patch test. Allergic reactions to chromium released from the stent might be one of the triggering mechanisms for in-stent restenosis and PSS after BMS implantation. <Learning objective: Peri-stent contrast staining (PSS) was an abnormal angiographic finding suggesting presence of contrast material outside the stent border after sirolimus-eluting stent implantation. However, PSS is rarely seen with bare-metal stents (BMSs), and PSS and refractory restenosis after BMS implantation suggests the relation with metal allergy. We must think of metal allergy after the development of refractory restenosis and PSS with BMS implantation.>.