[Anti-MuSK antibody positive myasthenia gravis with HIV infection successfully treated with cyclosporin: a case report].

A-58-year old man presented with fluctuating ptosis and dysphagia. When he was 53 years old, he developed oral candidiasis and serum human immunodeficiency virus (HIV) RNA was detected. After starting highly active antiretroviral therapy, serum HIV RNA became undetectable. Neurological examination revealed ptosis and bulbar symptoms. Myasthenia gravis was comfirmed by a positive edrophonium test, showing 20% decrement of the compound muscle action potential on repetitive stimulation. Anti-acetylcholine receptor antibodies were negative and anti-muscle specific tyrosine kinase (MuSK) antibodies were positive. The chest CT scan was normal. He experienced transient clinical remission with pyridostigmine bromide and prednisolone. However relapse occurred after he returned to work. Persistent clinical remission was first observed after cyclosporin administration. There are eleven reports in which patients had concomitant myasthenia gravis and HIV infection. Most of those cases were benign in clinical course and required only anticholinesterase therapy. In our case, however, anti-MuSK antibodies were positive, and symptoms of myasthenia gravis remained despite prednisolone administration. Cyclosporin is directly active against HIV, and thus, cyclosporine therapy may be helpful in patients with concomitant myasthenia gravis and HIV infection.