[P3-130] A pediatric case of Anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase antibody associated immune-mediated myopathy
【Introduction】
Anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) antibody associated immune-mediated myopathy is classified as a type of inflammatory myopathy. There are few reported pediatric cases, and the course and prognosis is unknown. Here, we present our experience with oral steroid treatment in a pediatric patient with the disease.
【Case】
We showed a six-year-old Japanese boy with this myopathy. We performed a muscle biopsy at 2 years and 4 months of age due to proximal-dominant muscle weakness and atrophy. Pathological findings showed no sign of inflammatory cell infiltration, but a few necrotic and some regenerating were noted, indicating chronic myogenic change. Although HLA-ABC staining was positive, the other myositis-related autoantibody tests were negative. At 6 years and 1 month, the patient tested positive for anti-HMGCR antibody. Thus, we diagnosed him as the myopathy and initiated oral steroid treatment. The patient could walk less than 10 m with assistance prior to the treatment, but this treatment improved to a kilometer of unassisted walking after two weeks of treatment.
【Discussion】
Although this disease is considered to remit and improve with immunosuppressive therapy including steroids, relapse can occur following dose reduction or discontinuation of treatment. This approach appears to be effective in children, as symptoms were ameliorated with steroid treatment.
【Conclusion】
Here, we reported a pediatric case of the myopathy. Steroid treatment may be effective for the myopathy.
Anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) antibody associated immune-mediated myopathy is classified as a type of inflammatory myopathy. There are few reported pediatric cases, and the course and prognosis is unknown. Here, we present our experience with oral steroid treatment in a pediatric patient with the disease.
【Case】
We showed a six-year-old Japanese boy with this myopathy. We performed a muscle biopsy at 2 years and 4 months of age due to proximal-dominant muscle weakness and atrophy. Pathological findings showed no sign of inflammatory cell infiltration, but a few necrotic and some regenerating were noted, indicating chronic myogenic change. Although HLA-ABC staining was positive, the other myositis-related autoantibody tests were negative. At 6 years and 1 month, the patient tested positive for anti-HMGCR antibody. Thus, we diagnosed him as the myopathy and initiated oral steroid treatment. The patient could walk less than 10 m with assistance prior to the treatment, but this treatment improved to a kilometer of unassisted walking after two weeks of treatment.
【Discussion】
Although this disease is considered to remit and improve with immunosuppressive therapy including steroids, relapse can occur following dose reduction or discontinuation of treatment. This approach appears to be effective in children, as symptoms were ameliorated with steroid treatment.
【Conclusion】
Here, we reported a pediatric case of the myopathy. Steroid treatment may be effective for the myopathy.