Anti-signal recognition particle antibody-positive immune-mediated necrotizing myopathy with inclusion body myositis-like features in a patient with human immunodeficiency virus and syphilis infection

Inclusion body myositis and immune-mediated necrotizing myopathy are inflammatory myopathies characterized by specific clinical and pathological features. Inclusion body myositis is associated with human immunodeficiency virus infection, whereas immune-mediated necrotizing myopathy is extremely rare in individuals positive for human immunodeficiency virus. To date, no reports have described the coexistence of immune-mediated necrotizing myopathy and inclusion body myositis-like pathological features in patients positive for human immunodeficiency virus. Herein, we report a rare case of a 40-year-old man with human immunodeficiency virus-associated subacute progressive myopathy presenting with simultaneous proximal and distal muscle weakness, dysphagia, and markedly elevated creatine kinase levels. Serological testing revealed strong positivity for anti-signal recognition particle antibodies. Muscle biopsy revealed coexisting pathological features suggesting both immune-mediated necrotizing myopathy and inclusion body myositis. The patient showed insufficient response to antiretroviral therapy and glucocorticoids; however, intravenous immunoglobulin therapy resulted in a marked clinical response. This case highlights the possible coexistence of immune-mediated necrotizing myopathy and inclusion body myositis-like pathology in the context of human immunodeficiency virus infection and provides insights into the pathophysiology of human immunodeficiency virus-associated myopathy. Furthermore, this report suggests the potential effectiveness of intravenous immunoglobulin treatment in such cases.