Symptomatic amyloid-related imaging abnormalities after Lecanemab treatment in an APOE ε4 homozygous patient with mild cognitive impairment due to Alzheimer's disease: one case report

doi:10.3969/j.issn.1672-6731.2026.08.011

Abstract

Abstract:

Objective: To report a case of symptomatic amyloid-related imaging abnormalities (ARIA) following Lecanemab treatment in patient with mild cognitive impairment due to Alzheimer's disease (AD-MCI), so as to provide references for the clinical safe application of anti β-amyloid (Aβ) monoclonal antibody. Methods and Results: A 63-year-old male patient presented with memory impairment. Mini-Mental State Examination (MMSE) score was 27. MRI showed mild bilateral hippocampal atrophy, and the Aβ-PET Centiloid value was 67.57 CL. Genetic testing identified an APOE ε4/ε4 homozygous genotype. After 4 infusions of Lecanemab, the patient developed severe fatigue, chest distress and decline in activities of daily living. MRI showed symptomatic amyloid-related imaging abnormalities-edema (ARIA-E) and amyloid-related imaging abnormalities-hemorrhage (ARIA-H). Significant resolution of cerebral edema was achieved after anti-inflammatory hormone therapy, yet cerebral microbleeds continued to increase. The MMSE score rose from 27 to 30, and activities of daily living remained stable. Conclusions: Cognitive function improved in the patient with AD-MCI after Lecanemab treatment; nevertheless, symptomatic ARIA-E and ARIA-H may occur as complications. Hormone therapy can alleviate cerebral edema. The APOE ε4/ε4 homozygous genotype represents a high-risk factor for ARIA, and patients often present with atypical symptoms.

Key words: Alzheimer disease, Cognition disorders, Amyloid beta-peptides, Antibodies, monoclonal, Magnetic resonance imaging, Brainedema, Cerebral hemorrhage, Case reports

摘要：

目的: 报告1例阿尔茨海默病源性轻度认知障碍患者接受仑卡奈单抗治疗后出现症状性淀粉样蛋白相关影像异常（ARIA）病例，为抗β-淀粉样蛋白（Aβ）单克隆抗体的临床安全应用提供参考。方法与结果: 患者为男性，63岁，临床表现为记忆力减退，简易智能状态检查量表（MMSE）评分27分；头部MRI显示双侧海马轻度萎缩，Aβ-PETCentiloid标准化尺度值为67.57CL；基因检测为APOE ε4/ε4纯合型。仑卡奈单抗静脉滴注4次后出现严重疲劳、胸闷、日常生活活动能力下降；头部MRI提示症状性淀粉样蛋白相关影像异常-水肿（ARIA-E）合并淀粉样蛋白相关影像异常-出血（ARIA-H）。经短期糖皮质激素抗炎症治疗后脑水肿缓解，但脑微出血灶持续增多；MMSE评分由27分升至30分，日常生活活动能力维持稳定。结论: 仑卡奈单抗对阿尔茨海默病源性轻度认知障碍患者的认知功能有改善作用，但可诱发症状性ARIA-E与ARIA-H，糖皮质激素冲击治疗可改善脑水肿；APOE ε4/ε4纯合型是ARIA高危因素且患者症状多不典型。

关键词: 阿尔茨海默病, 认知障碍, 淀粉样β肽类, 抗体，单克隆, 磁共振成像, 脑水肿, 脑出血, 病例报告

CLC Number:

R741.16

Wen-wei CAO, Jie-li GENG, Chen-hui JI, Wei-feng SUN, Ya-wen SUN, Gang WANG. Symptomatic amyloid-related imaging abnormalities after Lecanemab treatment in an APOE ε4 homozygous patient with mild cognitive impairment due to Alzheimer's disease: one case report[J]. Chinese Journal of Contemporary Neurology and Neurosurgery, 2026, 26(8): 879-886.

曹雯炜, 耿介立, 吉晨晖, 孙卫锋, 孙雅文, 王刚. 仑卡奈单抗治疗APOE ε4/ε4纯合型阿尔茨海默病源性轻度认知障碍后并发症状性淀粉样蛋白相关影像异常一例[J]. 中国现代神经疾病杂志, 2026, 26(8): 879-886.

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URL: https://journal11.magtechjournal.com/cjcnn/EN/10.3969/j.issn.1672-6731.2026.08.011

https://journal11.magtechjournal.com/cjcnn/EN/Y2026/V26/I8/879

Figures/Tables 5

Figure 1 HeadMRI findings on March 28, 2025Axial fat suppression T₂-FLAIR showed Fazekas grade was 2 (Panel 1a). Axial SWI showed no evidence of cerebral microbleeds (Panel 1b). Coronal T₁WI showed mild atrophy of the bilateral hippocampus, MTA score was 1 (Panel 1c).

Figure 2 PET findings obtained from March 28, 2025 to April 14, 2025 Sagittal ¹⁸F-Florbetapir PET showed abnormal Aβ deposition in the bilateral frontal lobes and posterior cingulate gyrus (Panel 2a). Coronal ¹⁸F-Florbetapir PET showed the abnormal Aβ deposition in the bilateral temporo-parietal cortices (Panel 2b). Axial ¹⁸F-Florbetapir PET showed abnormal Aβ deposition involving the bilateral frontal and occipital lobes, consistent with positive tau pathology (Panel 2c). Axial ¹⁸F-PI2620 PET showed increased radiotracer uptake in the bilateral precuneus lobes, which was consistent with positive tau pathology (Panel 2d). Coronal ¹⁸F-PI2620 PET showed increased radiotracer uptake in the bilateral temporal lobes (Panel 2e). Sagittal ¹⁸F-PI2620 PET showed increased radiotracer uptake in posterior cingulate gyrus and precuneus lobe(Panel 2f).

Figure 3 Outpatient MRI findings before Lecanemab treatment (September 5, 2025) Axial fat suppression T₂-FLAIR showed Fazekas grade was 2 (Panel 3a). Axial SWI showed no evidence of cerebral microbleeds (Panel 3b). Coronal T₁WI showed mild atrophy of the bilateral hippocampus, MTA score was 1, which was consistent with the baseline scan from March 28, 2025 (Panel 3c).

Figure 4 Timeline of Lecanemab treatment and clinical symptom changes.

Figure 5 The evolution process of the ARIA-E and ARIA-HAxial T₂-FLAIR (November 4, 2025) showed cortical swelling observed in the right temporal-parietal lobes and left parieto-occipital lobes. Extensive white matter hyperintensities was showed in the right parieto-occipital lobes, measuring approximately 60mm×45mm with ill-defined boundaries. Associated mild mass effect compressed the occipital horn of the right lateral ventricle. Focal, limited abnormal hyperintensity was visible within the left parieto-occipital lobes (Panel 5a). Axial SWI (November 4, 2025) showed around 10 scattered subcortical microbleeds detected in the right parietal lobe. These microbleeds were newly emergent compared with the baseline scan (March 28, 2025), consistent with concurrent ARIA-E and ARIA-H (Panel 5b). Axial T₂-FLAIR (November 7, 2025) showed diffuse periventricular white matter hyperintensities in bilateral paireto-occipital lobes, with greater prominence on the right. The right-sided lesion measured approximately 58mm×42mm with ill-defined boundaries, while the left-sided lesion spanned approximately 30mm×14mm (Panel 5c). Axial SWI (November 7, 2025) showed that approximately 10 subcortical microbleeds persisted in the right parietal lobe, with no obvious interval change compared with the prior scan (November 4, 2025; Panel 5d). Axial T₂-FLAIR (December 5, 2025) showed symmetric periventricular white matter hyperintensities in bilateral paireto-occipital lobes, with greater prominence on the right. The right-sided lesion measured was 36mm×23mm with ill-defined boundaries, and the left-sided lesion measured around 18mm×12mm (Panel 5e). Axial SWI (December 5, 2025) showed more than 20 microbleeds in the right parieto-occipital lobes; 2 new microbleeds were identified in the left occipital lobe (Panel 5f). Axial T₂-FLAIR (December 28, 2025) showed white matter hyperintensities with relatively clear boundaries observed bilaterally in the parieto-occipital lobes (Panel 5g). Axial SWI (December 28, 2025) showed multiple scattered microbleeds in the subcortical area of the right paireto-occipital lobes, and a few microbleeds in the subcortical area of the left occipital lobe. Findings showed no substantial change relative to the scan acquired on December 5, 2025 (Panel 5h). Axial T₂-FLAIR (April 18, 2026) showed patchy hyperintensities lesions in the bilateral parieto-occipital white matter, with well-defined boundaries. These findings were consistent with chronic small-vessel disease-related white matter hyperintensities (Fazekas scale grade 2). No changes were observed in the imaging findings during the second post-discharge follow-up examination conducted on December 28, 2025 (Panel 5i). Axial SWI (April 18, 2025) showed more than 10 scattered subcortical microbleeds were identified in the right parieto-occipital lobes (Panel 5j).

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