Concomitant Exacerbation of Graves Orbitopathy and Double-Seronegative Myasthenia Gravis after SARS-CoV-2 Infection

SARS-CoV-2 infection could trigger autoimmune disease. We report a case of concomitant exacerbation of Graves orbitopathy (GO) and myasthenia gravis (MG) after SARS-CoV-2 infection. A 43-year-old woman had diplopia, proptosis, and swollen eyelids. Blood tests showed thyrotoxicosis and positive thyroid-stimulating hormone receptor antibodies, and orbital magnetic resonance imaging (MRI) showed enlarged extraocular muscles. She was therefore referred to our hospital with diagnosis of GO. Methylprednisolone pulse therapy (MPT) in combination with orbital radiotherapy were performed for 3 weeks, and ocular symptoms improved. At 41 weeks, the patient was infected with SARS-CoV-2 and felt sudden worsening of diplopia and ptosis. MRI showed an enlarged right inferior rectus muscle. MPT and orbital radiotherapy were performed again for 3 weeks for the suspected GO, but there was insufficient improvement of the ptosis. Serum antiacetylcholine receptor and anti-muscle-specific tyrosine kinase antibodies were negative, but the patient was further evaluated with repetitive nerve stimulation test and ice pack test, and diagnosis was double-seronegative MG. Pyridostigmine treatment led to dramatic improvement of the ptosis. SARS-CoV-2 infection could exacerbate MG as well as GO. Careful diagnosis is required for ocular symptoms after SARS-CoV-2 infection, especially when there is double-seronegative MG.