A tumefactive demyelinating lesion in a person with MS after five years of fingolimod

A 38-year-old man with relapsing remitting multiple sclerosis (RRMS) developed a tumefactive demyelinating lesion (TDL) after being clinically and radiologically stable on fingolimod for the last five years. TDLs in MS tend to occur early on in the disease and are uncommon in longstanding MS. Compared to other immune modifying drugs used in MS, there is a relatively high and still increasing number of reports describing the development of TDL under treatment with fingolimod, suggesting a causal relation.