Histopathological Assessment of Asymptomatic Hydrophilic Polymer Emboli after Thrombectomy: A Case Report

Abstract

Objective: There have recently been reports of patients developing postprocedural symptoms due to hydrophilic polymer coating embolization, where pathological examination has revealed granulomas. Herein we report asymptomatic hydrophilic polymer embolism detected via pathological autopsy after mechanical thrombectomy.

Case Presentation: The patient was an 81-year-old woman who presented with sudden impaired consciousness, left hemiplegia, and an NIHSS score of 15. Magnetic resonance imaging showed right middle cerebral artery area infarction and complete M2 distal segment occlusion. A recombinant tissue-type plasminogen activator was administered and mechanical thrombectomy was performed, but reperfusion was not achieved. The patient died 27 days later. A pathological autopsy was performed, and multiple intravascular emboli were detected in the treated area. They were non-polarizing intraluminal foreign bodies with surrounding granulomatous inflammation. Asymptomatic hydrophilic polymer coating embolism was diagnosed. The foreign bodies were only detected in the right hemisphere, and they were also evident in the area where infarction did not occur.

Conclusion: Although the above-described complications are rarely symptomatic, we suggest that hydrophilic polymer embolization must be recognized as a common complication. Treatment should be provided when symptoms occur.