Amyloidosis is a shared name for several rare, complex and serious diseases caused by extra-cellular deposits of different misfolded proteins. Accurate characterization of the amyloid protein is essential for patient care. Immunoelectron microscopy (IEM) and laser microdissection followed by tandem mass spectrometry (LMD-MS) are new gold standards for molecular subtyping. Both methods perform superiorly to immunohistochemistry, but their complementarities, strengths and weaknesses across amyloid subtypes and organ biopsy origin remain undefined. Therefore, we performed a retrospective study of 106 Congo Red positive biopsies from different involved organs; heart, kidney, lung, gut mucosa, skin and bone marrow. IEM, performed with gold-labelled antibodies against kappa light chains, lambda light chains, transthyretin and amyloid A, identified specific staining of amyloid fibrils in 91.6%; in six biopsies amyloid fibrils were not identified, and in two, the fibril subtype could not be established. LMD-MS identified amyloid protein signature in 98.1%, but in nine the amyloid protein could not be clearly identified. MS identified protein subtype in 89.6%. Corresponding specificities ranged at organ level from 94-100%. Concordance was 89.6-100% for different amyloid subtypes. Importantly, combined use of both methods increased the diagnostic classification to 100%. Some variety in performances at organ level was observed.

中文翻译：

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免疫电子显微镜和质谱法对淀粉样沉积物进行分类。

淀粉样变性病是由几种错误折叠的蛋白质的细胞外沉积物引起的几种罕见，复杂和严重的疾病的统称。淀粉样蛋白的准确表征对于患者护理至关重要。免疫电子显微镜（IEM）和激光显微解剖，然后进行串联质谱（LMD-MS）是分子分型的新金标准。两种方法的性能均优于免疫组织化学，但它们在淀粉样蛋白亚型和器官活检起源之间的互补性，优势和劣势仍然不确定。因此，我们对来自不同受累器官的106例刚果红阳性活检进行了回顾性研究。心，肾，肺，肠粘膜，皮肤和骨髓。IEM，用针对κ轻链，λ轻链，运甲状腺素蛋白和淀粉样蛋白A的金标记抗体进行，鉴定出淀粉样原纤维的特异性染色率为91.6％；在六个活检组织中，未鉴定出淀粉样原纤维，而在两个活检中，无法确定原纤维亚型。LMD-MS识别出98.1％的淀粉样蛋白特征，但在9个中，淀粉样蛋白的识别不清楚。MS鉴定出89.6％的蛋白质亚型。相应的特异性在94-100％的器官水平范围内。不同淀粉样蛋白亚型的一致性为89.6-100％。重要的是，两种方法的组合使用将诊断分类提高到100％。在器官水平上观察到一些变化。但是在九种淀粉样蛋白中却无法清晰鉴定。MS鉴定出89.6％的蛋白质亚型。相应的特异性在94-100％的器官水平范围内。不同淀粉样蛋白亚型的一致性为89.6-100％。重要的是，两种方法的组合使用将诊断分类提高到100％。在器官水平上观察到一些变化。但是在九种淀粉样蛋白中却无法清晰鉴定。MS鉴定出89.6％的蛋白质亚型。相应的特异性在94-100％的器官水平范围内。不同淀粉样蛋白亚型的一致性为89.6-100％。重要的是，两种方法的组合使用将诊断分类提高到100％。在器官水平上观察到一些变化。