Background

Nemaline myopathies are congenital or acquired muscle disorders that typically present in childhood but can occasionally occur in adults with underlying malignant, infectious or autoimmune disorders. There is a great genetic heterogeneity as well as clinical variability among the disease.

Case presentation

Here, we present a case of nemaline myopathy in a young woman who was newly diagnosed with systemic lupus erythematosus (SLE) and Sjögren's overlap syndrome complicated by macrophage activation syndrome (MAS). She had no personal or family history of myopathy and was reporting progressive thigh weakness. A muscle biopsy revealed type 1 myofiber predominance with granular material in atrophic myocytes consistent with nemaline myopathy. Her symptoms markedly improved with immunotherapy for her SLE and MAS supporting the diagnosis of sporadic late-onset nemaline myopathy (SLONM) associated with her autoimmune disease.

Conclusions

SLONM is a type of nemaline myopathy that presents in adults and can occasionally be associated with autoimmune disease. In these cases, treatment of the underlying disorder with immunosuppression appears to improve symptoms of myopathy.