Title : A viral wake-up call in a patient with myasthenia gravis

Case description: An 80-year-old male with Myasthenia Gravis (MG) on azathioprine (50 mg qd) and pyridostigmine bromide (60 mg tid) presented with herpes zoster virus (HZV) on the right V1 of his face, with manifestation of herpes keratitis. He was treated and stabilized with prednisone, with no transient worsening of MG. The patient did not have a prior history of HZV vaccination. A positive prostate biopsy was additionally found.

Conclusions: We present a case of a patient without a history of HZV vaccination on a standard MG treatment regimen, including the use of azathioprine, who developed HZV and a positive prostate biopsy. This highlights the importance of adequate screening and preventive care of patients with MG on immunosuppressants to prevent opportunistic infections and potential for malignancy.

Clinical significance: Pyridostigmine bromide is considered first-line therapy for MG, with additional use of immunosuppressants for refractory MG. Azathioprine is a commonly prescribed maintenance treatment for MG due to its ability to suppress cell-mediated hypersensitivity and inhibit autoantibody production while preventing long-term corticosteroid use.

Due to immunosuppression from azathioprine, patients have an increased likelihood of developing infections, including latent reactivation of VZV, and malignancies, particularly lymphoma and skin cancer. The recombinant zoster vaccine (RZV) is a highly effective subunit vaccine, recommended among immunocompetent adults aged > 50 years old and immunosuppressed patients > age of 19, with 97.6% efficacy in patients > the age of 70.

Infection risk associated with azathioprine is acknowledged by the U.S. Food and Drug Administration (FDA), with a lack of established protocols beyond the general boxed warning. Additionally, guidelines discussing MG treatment fail to include vaccination prophylaxis as preventive care for this population, although indicated. More comprehensive protocols for the treatment of MG, including preventive strategies, are needed to mitigate adverse effects from immunomodulatory medications like azathioprine.

To be updated shortly..