Sporadic late-onset nemaline myopathy with monoclonal gammopathy of undetermined significance (SLONM-MGUS): An alternative treatment using cyclophosphamide-thalidomide-dexamethasone (CTD) regimen.

Sporadic late-onset nemaline myopathy with monoclonal gammopathy of undetermined significance is a rare subacute adult-onset myopathy. Without appropriate treatment, the prognosis is unfavorable and can be fatal. Various efficacious treatment options have been reported. High dose melphalan followed by autologous stem cell transplantation is the most used option with favorable outcome. Nevertheless, potentially safer alternative regimens await exploration. Here, we report the case of sporadic late-onset nemaline myopathy with monoclonal gammopathy of undetermined significance in a 33-year-old man with significant clinical improvement and complete remission of monoclonal gammopathy after 5 cycles of cyclophosphamide, thalidomide, and dexamethasone regimen. The regimen may be considered as an alternative option for patients with sporadic late-onset nemaline myopathy with monoclonal gammopathy of undetermined significance that are ineligible for upfront high-dose melphalan with autologous stem cell transplantation or that are being treated in resource-limited settings. Longer-term follow-up is needed to determine the long-term effectiveness of the cyclophosphamide, thalidomide, and dexamethasone regimen.