Researchers Discover New, Rare Autoimmune Disease

A previously unknown autoimmune muscle disease involving sudden onset of debilitating muscle pain and weakness has been identified by researchers at Washington University School of Medicine in St. Louis, Mo. They named the disease large-histiocyte-related immune myopathy. According to the researchers, the syndrome can easily be mistaken for other muscle diseases that require different treatment, so the findings are expected to help physicians treat patients appropriately.

The study involved a retrospective review of records and muscle pathology of four patients whose clinical features included muscle pain and proximal, symmetric, moderate to severe weakness in the arms and legs progressing over one week to four weeks. Associated systemic disorders in the patients included anemia in all, and hemophagocytic lymphohistiocytosis, hepatic disease, Raynaud phenomenon, metastatic cancer and cardiomyopathy in one patient each. In addition, patients presented with very high serum creatine kinase levels ranging from 10,000 to 102,000 U/L. Three of the patients improved when treated with immunomodulating therapy such as steroids and have not relapsed since. The fourth was undergoing cancer treatment when the muscle symptoms developed, and he died due to cancer shortly afterward.