A Chinese retrospective study of 17 individuals with sporadic late-onset nemaline myopathy (SLONM), including four with monoclonal gammopathy of undetermined significance (MGUS), shows positive muscle biopsy immunostaining for anti-α-actinin antibodies in all cases.
- The first signs appeared at a median age of 54 years.
- Most had asymmetric proximal limb muscle involvement (71%) and neck extensors (53%) with head droop at first evaluation (41%).
- Muscle MRI showed preferential involvement of the paravertebral, gluteus minimus and medius, semimembranosus and soleus muscles.
- Twelve patients (71%) had a follow-up of 5 months to 8 years :
. three of the four patients with MGUS received autologous stem cell transplantation resulting in moderate muscle improvement and complete hematologic remission ;
. the fourth patient was treated with prednisone for 16 months with moderate improvement and a relapse several months after stopping the corticosteroids ;
. one patient with unknown hematological status was treated with low doses of prednisone and died eight years later ;
. six patients without MGUS received corticosteroids combined with immunosuppressive therapy, preceded for three of them by one to three courses of IV immunoglobulin: three had complete remission, while the other three had moderate improvement.
