Efgartigimod-associated Kaposi's varicelliform eruption and herpetic conjunctivitis in a patient with seropositive ocular myasthenia gravis: a case report and review.

Background: Efgartigimod (Efgartigimod alpha fcab, Vyvgart™) is a pioneering neonatal Fc receptor (FcRn) antagonist for the treatment of severe autoimmune diseases mediated by pathogenic immunoglobulin G (IgG) autoantibodies, including myasthenia gravis (MG). It is a well-tolerated drug with minor side effects, such as headache and upper respiratory (lung) and urinary tract infections. Here, we present a case of Kaposi's varicelliform eruption (KVE) and herpetic conjunctivitis related to efgartigimod in a 60-year-old patient with ocular MG (OMG). Case description: A 60-year-old Chinese male suffered from acetylcholine receptor antibody positive (AChR Ab+) OMG for 8 years. During this period, he underwent first-line treatment with systemic corticosteroids, cyclosporine, cyclophosphamide, and so on, but had poor symptom improvement. On the recommendation of his attending neurologist, he received one cycle of intravenous efgartigimod (10mg/kg, once weekly for 4 weeks). The patient experienced fever, widespread painful blisters, and edema on the face on the third day after his last intravenous infusion. The patient also complained of increased secretions and a foreign body sensation in both eyes. Laboratory tests confirmed infection with herpes simplex virus (HSV). A diagnosis of efgartigimod-associated KVE and herpetic conjunctivitis was made. After intravenous administration (5mg/kg, 3 times a day, every 8 hours) for 10 days, the patient was cured without residual complications. Conclusions: This case is the first report of a patient with KVE and herpetic conjunctivitis related to efgartigimod in PubMed. This is rare and unusual. Clinicians should be alert to the rare symptoms related to efgartigimod.