Lohani Sadichhya, Schuiteman Emily, Garg Lohit, Yadav Dhiraj, Zarouk Sami
Department of Internal Medicine, Beaumont Health, Royal Oak, MI 48073, USA.
Lehigh Valley Health Network, Allentown, PA 18103, USA.
Case Rep Nephrol. 2016;2016:8690642. doi: 10.1155/2016/8690642. Epub 2016 Oct 20.
Hereditary amyloidoses are rare and pose a diagnostic challenge. We report a case of hereditary amyloidosis associated with apolipoprotein C-II deposition in a 61-year-old female presenting with renal failure and nephrotic syndrome misdiagnosed as light chain amyloidosis. Renal biopsy was consistent with amyloidosis on microscopy; however, immunofluorescence was inconclusive for the type of amyloid protein. Monoclonal gammopathy evaluation revealed kappa light chain. Bone marrow biopsy revealed minimal involvement with amyloidosis with kappa monotypic plasma cells on flow cytometry. She was started on chemotherapy for light chain amyloidosis. She was referred to the Mayo clinic where laser microdissection and liquid chromatography mass spectrometry detected high levels of apolipoprotein C-II, making a definitive diagnosis. Apolipoprotein C-II is a component of very low-density lipoprotein and aggregates in lipid-free conditions to form amyloid fibrils. The identification of apolipoprotein C-II as the cause of amyloidosis cannot be solely made with routine microscopy or immunofluorescence. Further evaluation of biopsy specimens with laser microdissection and mass spectrometry and DNA sequencing of exons should be done routinely in patients with amyloidoses for definitive diagnosis. Our case highlights the importance of determining the subtype of amyloidosis that is critical for avoiding unnecessary therapy such as chemotherapy.
遗传性淀粉样变性病较为罕见，诊断颇具挑战。我们报告一例61岁女性遗传性淀粉样变性病病例，该患者伴有载脂蛋白C-II沉积，最初因肾衰竭和肾病综合征被误诊为轻链淀粉样变性病。肾活检在显微镜下符合淀粉样变性病表现；然而，免疫荧光检查对于淀粉样蛋白类型的诊断尚无定论。单克隆丙种球蛋白病评估显示κ轻链。骨髓活检显示淀粉样变性病累及程度轻微，流式细胞术检测到κ单型浆细胞。她开始接受针对轻链淀粉样变性病的化疗。随后她被转诊至梅奥诊所，在那里通过激光显微切割和液相色谱质谱联用技术检测到高水平的载脂蛋白C-II，从而得以明确诊断。载脂蛋白C-II是极低密度脂蛋白的一个组分，在无脂质条件下会聚集形成淀粉样纤维。仅通过常规显微镜检查或免疫荧光检查无法确定载脂蛋白C-II为淀粉样变性病的病因。对于淀粉样变性病患者，应常规采用激光显微切割和质谱联用技术进一步评估活检标本，并对外显子进行DNA测序以明确诊断。我们的病例凸显了确定淀粉样变性病亚型的重要性，这对于避免诸如化疗等不必要的治疗至关重要。
