Teaching NeuroImage: Cryptococcus in a Woman With Multiple Sclerosis on Fingolimod

A 33-year-old woman with relapsing remitting multiple sclerosis who was on fingolimod for 5 years presented with a solitary skin lesion on her abdomen (Figure 1) for 2 months, which was unresponsive to antibiotics. The neurologic examination was normal. She denied having infectious symptoms, chest pain, shortness of breath, recent travel, trauma to the area, or animal exposure. Her most recent absolute lymphocyte count was 0.22 × 10⁹/L (reference 1.2-4.0 10⁹/L). The differential diagnosis included skinfold friction, dermatofibroma, pyoderma gangrenosum, and basal cell carcinoma. Although a dermatologist did not initially recommend a biopsy because the lesion was not ulcerated, she obtained one based on the recommendation of her neurologist. Shave biopsy revealed cryptococcal fungal infection (Figure 2). There was no evidence of asymptomatic disseminated cryptococcus. The proposed mechanism for the lesion involves a latent infection while immunocompetent with reactivation once immunocompromised.¹ Cryptococcus infections are associated with immunosuppression, most often due to human immunodeficiency virus infection, and only 6 fingolimod-associated cutaneous infections have been reported in the literature.² Patients with MS on immunosuppressant medication should be carefully screened for cutaneous infections.