New-onset Myasthenia Gravis after SARS-CoV-2 infection: case report and literature review.

We report the case of a 19-year-old female patient who developed Myasthenia Gravis 13 days after SARS-CoV-2 infection with positive RT-PCR testing. Her symptoms initially involved the oculo-bulbar district, but they gradually worsened in 3 months converting into a generalized form of Myasthenia Gravis complicated with a myasthenic crisis. A high level of anti-acetylcholine receptor antibodies was found in the serum, while anti-MuSK antibodies were negative; Repetitive Nerve Stimulation and Single-fiber Electromyography were suggestive of Myasthenia Gravis. Intravenous immunoglobulin courses and specific therapy were able to improve her symptoms, but thymic resection was needed to control the disease. This is a report of new-onset Myasthenia Gravis correlated to COVID-19 in which thymic resection was described and the histologic analysis of the thymus was performed showing thymic hyperplasia despite negative thoracic Magnetic Resonance Imaging. SARS-CoV-2 infection releases inflammatory cytokines that could dysregulate the immune system and lead to Myasthenia Gravis in susceptible subjects.