To examine the impact of mycophenolate mofetil (MMF) and azathioprine (AZA) on the incidence of development of skin lesions in patients with myasthenia gravis (MG).

International consensus guidelines for the management of MG recommend the use of nonsteroidal immunosuppressive agents, such as MMF and AZA. These agents may increase the risk of malignancies due to chronic suppression of cell-mediated immunity. Limited information exists on the risk of skin cancer in immunosuppressed patients with MG.

This is a single center, cohort study of patients with MG. Retrospective chart review was conducted to gather demographic data, MG history and management. Patients were contacted via EHR patient message, telephone, and/or during clinic appointment to request participation in a standardized survey to assess past and current skin issues. Patients were assigned to either non-exposed or exposed groups, determined by treatment with MMF or AZA for ≥ 12 months.

Of 194 total patients in MG clinic population, 143 patients met inclusion criteria and were contacted to request participation. Majority (67%) of cohort were white, with median age of 67 years (IQR 48-74), and 56% identifying as female. A total of 103 patients (72%) responded to the survey, with 61 patients (60%) in the exposed group and the remaining 40% being either naïve to these agents or exposed for < 12 months. Of those surveyed, 69% and 16% had been exposed to MMF or AZA for ≥ 12 months, respectively.

Per the patient-reported survey, we found that 10% and 33% of patients developed new skin lesions after initiation of MMF and AZA, respectively, whereas 40% of patients reported skin conditions in the non-exposed group.

Based on this large MG cohort survey study we found no difference of skin lesion incidence in patients exposed to MMF or AZA compared to the non-exposed group.