从“不明原因心力衰竭”到确诊：IgD-λ型 原发性系统性淀粉样变性心肌受累1例报告

From “Unexplained Heart Failure” to Final Diagnosis: A Case Report of IgD-λ Type Primary Systemic Amyloidosis with Cardiac Involvement

摘要: 目的：原发性系统性淀粉样变性(primary systemic amyloidosis, AL型)心脏受累起病隐匿，易误诊。IgD-λ型罕见，常规免疫固定电泳易漏诊。本文报道1例以心力衰竭为首发表现的IgD-λ型病例，提高对该病诊断陷阱的认识。方法：回顾性分析1例41岁女性患者的临床资料，总结诊断过程及关键检查。结果：心脏超声示室间隔与左室后壁增厚，心电图示多部位传导异常，呈“心肌肥厚–心电图矛盾”。血游离轻链κ/λ比值0.23，骨髓浆细胞占6.5%~9%，但首次常规免疫固定电泳阴性。加做IgD/IgE分型后检出IgD-λ型单克隆免疫球蛋白，心脏MRI符合心肌淀粉样变，确诊为原发性系统性淀粉样变性(IgD-λ型，伴1q21扩增、RB1/13q34缺失，心脏梅奥III期)。8疗程BCD方案后血液学反应不佳(κ/λ比值0.23→0.24，BNP降幅21.5%)，因经济原因拒绝达雷妥尤单抗，改RD方案后失访。结论：不明原因心力衰竭合并左室肥厚与心电图传导异常时，应警惕心脏淀粉样变性。常规免疫固定电泳阴性不能排除诊断，应主动加做IgD/IgE分型及游离轻链检测。IgD-λ型可能对常规硼替佐米方案敏感性差，需早期评估疗效并及时升级治疗。

Abstract: Objective: Cardiac involvement in primary systemic amyloidosis (AL-type) is insidious and easily misdiagnosed. The IgD-λ subtype is rare and often missed by conventional immunofixation electrophoresis (IFE). This case report aims to improve awareness of diagnostic pitfalls. Methods: Retrospective analysis of a 41-year-old female patient presenting with heart failure. Results: Echocardiography showed septal and posterior wall thickening; electrocardiogram (ECG) revealed multiple conduction abnormalities (“hypertrophy-ECG paradox”). Serum free light chain κ/λ ratio was 0.23, bone marrow plasma cells 6.5%~9%, but initial conventional IFE was negative. After performing IgD/IgE typing, IgD-λ monoclonal immunoglobulin was detected. Cardiac MRI was consistent with myocardial amyloidosis. The final diagnosis was primary systemic amyloidosis (IgD-λ type, with 1q21 amplification and RB1/13q34 deletion, Mayo stage III). After 8 cycles of BCD regimen, the hematologic response was poor (κ/λ ratio 0.23→0.24, BNP decreased by 21.5%). Due to financial reasons, the patient refused daratumumab and switched to RD regimen, then was lost to follow-up. Conclusion: Unexplained heart failure with left ventricular hypertrophy and ECG conduction abnormalities should raise suspicion for cardiac amyloidosis. Negative conventional IFE does not exclude the diagnosis; IgD/IgE typing and free light chain testing should be actively performed. IgD-λ type may have poor sensitivity to conventional bortezomib-based regimens, requiring early efficacy assessment and timely treatment escalation.