Warts and all: Fingolimod and unusual HPV-associated lesions

Background: Fingolimod is used to reduce relapse rates in relapsing-remitting multiple sclerosis (MS). It is a sphingosine 1-phosphate (S1P) analogue having antagonistic effects on S1P receptors. Its immunosuppressive effect is due to reduced circulating lymphocyte numbers, and it may also be associated with impaired intrinsic cancer surveillance. Fingolimod side effects include increased rates and severity of viral infections particularly varicella zoster. Methods: We present five cases of chronic and treatment refractory warts associated with fingolimod therapy. Results: Each of the five cases presenting with chronic warts while receiving fingolimod therapy had prolonged periods of lymphopenia and improvements were seen following dose reduction or cessation of fingolimod. Conclusion: Cutaneous warts are associated with human papilloma virus (HPV) infection, suggesting an increased risk of other HPV-driven conditions such as cervical cancer following fingolimod administration. HPV viruses are responsible for approximately 90% of cervical cancers as well as a significant portion of anogenital cancers and have a high prevalence in sexually active adults. Given the reduced immune response to viral infections and potential impaired cancer surveillance in those receiving fingolimod, HPV vaccination and frequent assessment for the development of HPV-associated malignancies are recommended.