Tumefactive demyelinating lesions as a first clinical event: Clinical, imaging, and follow-up observations.

BACKGROUND: Tumefactive demyelinating lesions (TDLs) are associated with a variety of demyelinating diseases in the central nervous system (CNS). However, there are no current guidelines describing how to classify and treat patients with this rare phenotype. Thus, the present study aimed to determine the long-term evolution and disease course of patients initially presenting with TDLs and to describe their clinical and radiographic characteristics. METHODS: From the National Cancer Center registry of inflammatory diseases of the CNS, 31 patients initially presenting with TDLs with follow-up for at least 12 months were enrolled and their demographic, clinical, and radiographic characteristics were evaluated. RESULTS: The median follow-up duration was 37.6 months, during which time 11 patients were diagnosed with neuromyelitis optica spectrum disorder (NMOSD), seven with multiple sclerosis (MS), and 11 remained idiopathic; six did not experience any further clinical events (isolated demyelinating syndrome), and five patients experienced recurrent demyelinating events that were not consistent with either MS or NMOSD. Of the remaining two patients, one was diagnosed with hyperthyroidism-associated demyelination and one with tacrolimus-induced demyelination. CONCLUSIONS: The majority of TDLs evolve into MS or NMOSD. However, despite extensive diagnostic work-ups and long-term follow-ups, the etiology of TDLs was unknown for some patients.