Macrophage activation syndrome in a case of Myasthenia gravis with concurrent cytomegalovirus infection

Objective: Macrophage activation syndrome (MAS) or reactive hemophagocytic lymphohistiocytosis (HLH) refers to a set of clinical symptoms caused by the excessive activation and proliferation of macrophages. It was linked with autoimmune disease such as systemic-onset juvenile rheumatoid arthritis, systemic lupus erythematosus, rheumatoid arthritis, and dermatomyositis, etc. Herein we report a case of myasthenia gravis (MG) with concurrent cytomegalovirus (CMV) infection developed MAS. Case report: A 31-year-old female with history of MG for 2 years under stable control with azathioprine and prednisolone. She presented with persistent high fever for 2 weeks after an upper respiratory infection. Lab data revealed pancytopenia, elevated triglyceride, ferritin and C-reactive protein (CRP). A bone marrow aspiration confirmed hemophagocytosis. Investigation for occult infection revealed her plasma was positive for CMV IgG and IgM, and high for CMV viral load. She was then treated with 5 sessions of plasmapheresis and pulse steroid. Azathioprine was discontinued and replaced with cyclosporine. Gancylovir was given for her concurrent CMV infection. After 2 weeks of treatment, her fever gradually subsided, and her blood cell count, hepatobiliary enzymes, ferritin and CRP have returned to normal range. She was discharged in good recovery. Conclusion: MAS is a rare complication of systemic autoimmune disease with poor prognosis, which may be precipitated by concurrent infection. Early recognition of this syndrome and prompt immune modulation therapy is crucial for successful treatment.