Abstract WP281: Histologic Features of Thrombi Retrieved From Ischemic Stroke Patients With Cancer

Abstract

Background: Systemic cancer is a cause of stroke. However, histologic features of thrombus in stroke patients with cancer are not well-known. We investigated histologic features of intracranial thrombi in acute stroke patients with cancer. Methods: We prospectively collected thrombi that were retrieved during mechanical thrombectomy. This study included 32 consecutive patients with any history of systemic cancer (16 patients with active cancer and 16 patients with inactive cancer.) All patients underwent continuous electrocardiographic monitoring for at least 24 h. Echocardiography was performed in all but three patients. Immunohistochemical staining of thrombus was done using anti-CD42b antibody for platelets, anti-glycophorin antibody for erythrocytes, anti-fibrinogen antibody for fibrin, anti-myeloperoxidase antibody for leukocytes, and anti-Histone H3 antibody for neutrophil extracellular traps. After acquiring images of entire thrombus area using the stereo investigator imaging system, quantitative fraction (%) of different thrombus composition was semi-automatically assessed using ImageJ software. We compared the thrombus composition between the active cancer group and the inactive cancer group. Results: Comparing with the inactive cancer group, the active cancer group showed higher platelet fraction (median [interquartile range], 20.6 [7.3-27.6] vs 6.1 [2.5-9.9], p=0.002) and lower erythrocyte fraction (1.6 [0.8-11.1] vs 20.7 [13.3-23.7], p=0.001). Fractions for fibrin, leukocytes, and neutrophil extracellular traps were not different between the active and inactive cancer groups. Four patients had vegetation on echocardiography and showed very high platelet fraction (29.5 [26.1-33.9]) and very low erythrocyte fraction (0.8 [0.7-0.9]). Of the active cancer group, 6 patients with negative evaluation also showed high platelet fraction and low erythrocyte fraction, but the thrombus composition in 4 patients with determined etiology (3 atrial fibrillation, 1 >50% stenosis) was similar to that in inactive cancer. Conclusion: Thrombi in stroke patients with active cancer were platelet-rich and erythrocyte-poor. These findings may aid to determine the treatment strategy for stroke patients with cancer.