Myeloma-Associated Sporadic Late-Onset Nemaline Myopathy, Successfully Treated with Daratumumab Based Induction and Autologous Stem Cell Transplantation: A Case Report.

Sporadic late-onset nemaline myopathy (SLONM) is a rare, acquired myopathy often associated with monoclonal gammopathy. We report a 48-year-old man presenting with progressive proximal and truncal muscle weakness in whom SLONM associated with smoldering myeloma was highly suspected. He received daratumumab, lenalidomide, and dexamethasone followed by high-dose melphalan with autologous stem cell transplantation and posttransplant therapy. Treatment resulted in marked improvement in muscle strength and performance status. The patient achieved minimal residual disease negativity and has remained relapse-free for 5 years. This case highlights the potential efficacy of daratumumab-based therapy followed by transplantation in SLONM associated with plasma cell dyscrasia. Trial Registration: The authors have confirmed clinical trial registration is not needed for this submission.