A 49-Year-Old Man with Combined Myasthenia Gravis, Autoimmune Thyroiditis and IgG4 Orbitopathy

Background: Patients with autoimmune thyroid disease have higher risk of myasthenia gravis, especially the ocular form of myasthenia gravis. IgG4-related disease and autoimmune thyroiditis have been reported to coexist; and IgG4- related thyroiditis pertain higher autoantibodies when compared with non-IgG4 thyroiditis. However, combined occurrence of myasthenia gravis, autoimmune thyroiditis, and IgG4-related disease has not been reported before. Methods: Here we report a case of ocular myasthenia gravis combined with autoimmune thyroiditis and elevated serum IgG4 that initially deteriorated to generalized myasthenia gravis after 3 days of intravenous (IV) pulse methylprednisolone treatment, but was rescued after plasma exchange therapy. The patient was placed on oral prednisolone, azathioprine, pentoxifylline, hydroxychloroquine, but the ocular symptoms relapsed occasionally when he felt tired. Another eight sessions of weekly IV pulse methylprednisolone were administered during outpatient clinic follow-ups. Findings: There was no more deterioration to generalized myasthenia gravis, and his ocular symptoms fully recovered after the treatment. He finally underwent thoracoscopic thymectomy, and pathology shows atrophic thymus. All immunosuppressants were tapered off after surgery, and he remained symptomfree on the last follow-up, about half a year after surgery. Conclusion: Since thyroid associated orbitopathy and IgG4-related orbitopathy respond well to steroid treatment, initial deterioration of concomittent ocular myasthenia gravis to generalized form after IV pulse steroid therapy can be rescued by plasmapheresis, and the follow-up IV pulse steroid therapy should not be precluded as the definitive treatment in this situation. Finally, all immunosuppressants were successfully discontinued and he remained symptomfree after surgical removal of the atrophic thymus.