SLONM-MGUS—M蛋白血症を伴う孤発性成人発症型ネマリンミオパチー

Sporadic Late-Onset Nemaline Myopathy Associated with MGUS

孤発性成人発症型ネマリンミオパチーは進行性の筋力低下を呈する稀な疾患であり，血清CK値も正常なことから，運動ニューロン疾患と誤診される可能性がある。中でも意義不明のM蛋白血症を合併する症例は予後不良であり，各種免疫療法の効果は乏しく，患者は数年の経過で呼吸不全から死亡に至ることが多い。近年，本疾患の治療として高用量化学療法に続く自己末梢血幹細胞移植が奏効するとの報告が散見され，注目されている。

Abstract

Sporadic late-onset nemaline myopathy is an uncommon disease. Clinically, it is characterized by progressive muscle weakness that can develop in limbs or axial muscles. Asymmetrical distal weakness, facial weakness, dropped head, and dysphagia can also occur. Since the serum creatine kinase level usually remains within the normal range, patients can be misdiagnosed with motor neuron disease. Recognition of nemaline rods on muscle biopsy is crucial for accurate diagnosis. If it is associated with monoclonal gammopathy of undetermined significance, the outcome is known to be unfavorable. In spite of various immunotherapies such as corticosteroids, immunosuppressants, and plasmapheresis, most patients die of respiratory failure within 5 years. Since the efficacy of autologous stem cell transplantation following high-dose melphalan was first reported in 2008, there have been accumulating reports that showed the positive effect of this therapy for the disease.