BI20 A case of fingolimod-associated Kaposi sarcoma in a patient with multiple sclerosis

Abstract

A 46-year-old Hungarian woman was referred via the suspected skin cancer pathway with an asymptomatic 15 × 15-mm erythematous shiny plaque on the right lower leg present for 6 weeks. She had a similar smaller lesion on the left inner thigh. She had a background of relapsing–remitting multiple sclerosis well controlled with fingolimod for 13 years. She was otherwise well with no systemic symptoms. A diagnostic biopsy showed Kaposi sarcoma (KS) with human herpesvirus (HHV)-8 and CD31 positivity. Further investigations revealed normal full blood count (except lymphopenia associated with fingolimod), normal renal and liver function, negative HIV test, and a positron emission tomography–computed tomography scan with incidental tiny foci of uptake in the thyroid and left breast. Our impression was immunosuppression-­related KS secondary to fingolimod, given her demographic and negative HIV status and given that Hungary is not an endemic country. After liaison with her neurologist fingolimod was stopped indefinitely. Her case was discussed by the skin cancer multidisciplinary team and treatment options included surgical excision of KS lesions or active monitoring for regression while off immunosuppression. The patient opted for the latter and requested her care was transferred to the same trust as her neurologist to facilitate surveillance. Immunosuppression significantly increases KS risk by impairing immune control over HHV-8 replication and tumour development. Fingolimod reduces the number of autoreactive T cells crossing the blood–central nervous system barrier in multiple sclerosis. Selective binding to sphingosine-1-phosphate receptors on circulating T-cell lymphocytes causes sequestration into lymph nodes and peripheral lymphopenia. This action impairs immune surveillance against oncogenic viruses like HHV-8. Fingolimod-related KS appears to be an extremely rare adverse event. At the time of writing there are only a handful of other reported cases in the literature.