Histopathological Evaluation of In Situ and Distal Embolic Thrombi of a Symptomatic Carotid Web: A Case Report

Carotid web (CW) is a fibrous hyperplasia of the intima confined to the carotid bulb, which often causes cerebral infarction and is refractory to medical treatment. Effective medical therapies should be explored. We report a case in which histopathological investigation of thrombus formation was performed for in situ CW and distal embolus. A man in his 40s was admitted to our hospital with an acute right M2 occlusion. Complete recanalization was achieved through mechanical thrombectomy. A thrombus is a combination of platelets, erythrocytes, and fibrin. There was a small CW-like angiographic finding; however, dual antiplatelet therapy (DAPT) with 100-mg aspirin and 75-mg clopidogrel was administered without recurrence. Carotid ultrasonography revealed thrombosis in the CW that decreased gradually. Because no potential embolic source was found on extensive cardiac examination, CW was considered as the cause of the embolism, and carotid endarterectomy (CEA) was successfully performed 3 months after onset. Histopathological examination of the resected CW revealed a platelet-rich thrombus in the recess. We speculated that the mixed thrombus causing the M2 embolism was the secondary thrombus formed on an in situ platelet-rich CW thrombus. Although antiplatelet therapy may have been effective in reducing the formation of the secondary mixed thrombus in this case, further cases and supporting evidence are needed.