Hull K M, Griffith L, Kuncl R W, Wigley F M
National Institutes of Health, Bethesda, Maryland 20892, USA.
Arthritis Rheum. 2001 Aug;44(8):1954-8. doi: 10.1002/1529-0131(200108)44:8<1954::AID-ART333>3.0.CO;2-S.
Amyloid myopathy is a well-described, increasingly recognized clinical entity. Similar to inflammatory myopathies, amyloid myopathy presents with proximal muscle weakness and can be associated with elevated levels of muscle enzymes. We report the case of a 58-year-old woman who, at presentation to her physician with proximal muscle weakness and congestive heart failure, was antinuclear antibody positive and had muscle biopsy findings "consistent with inflammatory myopathy." She was referred to Johns Hopkins University Medical Center with the diagnosis of polymyositis. Further investigation revealed a monoclonal gammopathy, a unique patterning of subcutaneous fat reticulation and hypodense bone marrow changes on magnetic resonance imaging (MRI), and an endocardial biopsy sample that was positive for light chain amyloid deposition. Paraffin sections of the muscle biopsy sample from the time of her original presentation were obtained, and Congo red staining showed diffuse amyloid deposition throughout the sample, but no inflammation. This case not only illustrates that proximal muscle weakness due to primary amyloid myopathy (as found in light chain amyloidosis and transthyretin amyloidosis) can mimic that of polymyositis, but also shows that unique findings on MRI can alert the clinician to the diagnosis of amyloidosis prior to muscle biopsy.
淀粉样变肌病是一种已被充分描述且日益被认识的临床实体。与炎性肌病相似，淀粉样变肌病表现为近端肌无力，且可能伴有肌肉酶水平升高。我们报告一例58岁女性病例，该患者因近端肌无力和充血性心力衰竭就诊于医生时，抗核抗体呈阳性，肌肉活检结果“符合炎性肌病”。她被诊断为多发性肌炎并转诊至约翰·霍普金斯大学医学中心。进一步检查发现单克隆丙种球蛋白病、磁共振成像（MRI）上皮下脂肪网状结构的独特模式和低密度骨髓改变，以及心内膜活检样本中轻链淀粉样沉积呈阳性。获取了她最初就诊时肌肉活检样本的石蜡切片，刚果红染色显示整个样本弥漫性淀粉样沉积，但无炎症。该病例不仅说明原发性淀粉样变肌病（如轻链淀粉样变性和转甲状腺素蛋白淀粉样变性中所见）导致的近端肌无力可酷似多发性肌炎，还表明MRI上的独特表现可在肌肉活检前提醒临床医生注意淀粉样变性的诊断。
