Sporadic late‐onset nemaline myopathy as a rare cause of slowly progressive muscle weakness with young adult onset

INTRODUCTION: Sporadic late-onset nemaline myopathy (SLONM) is a rare intractable acquired myopathy characterized by progressive muscle weakness and atrophy, usually with middle to late adult onset. Autologous peripheral blood stem cell transplantation (auto-PBSCT) has been reported to be a promising treatment for SLONM. METHODS: In this study we performed clinical characterization, muscle histopathological analysis, and muscle power monitoring after auto-PBSCT in a 27-year-old HIV-negative man with monoclonal gammopathy. RESULTS: He showed improved muscle strength after treatment with high-dose melphalan and auto-PBSCT. CONCLUSIONS: Considering the recent reports of successful treatment of SLONM, early and correct diagnosis of this condition in association with monoclonal gammopathy is important. SLONM should be added to the list of diseases to consider in the differential diagnosis of progressive muscle weakness with young adult onset.