Ana Paula Sieben Samek1, M.Cecilia Pita1, Ricardo Alonso1
1Neurology, MS and Demyelinating Diseases working group Hospital J.M. Ramos Mejía
Objective:
The aim of this study is to describe the demographic, clinical, and radiological characteristics of patients whose first MS manifestation was associated with tumefactive demyelinating lesions (TDLs) in a Latin American cohort.
Background:
TDLs are large plaques (≥ 2 cm) characterized by mass effect, perilesional edema, and contrast enhancement. Although uncommon, reported in only 1.4–8.2% of multiple sclerosis (MS) cases, they pose a significant diagnostic challenge due to their radiological resemblance to tumors, abscesses, or inflammatory encephalitis.
Design/Methods:
A retrospective study was conducted including patients diagnosed with MS who were evaluated at a tertiary referral center in Argentina between 2006 and 2025 . Clinical records,brain and spinal MRI scans and laboratory data were reviewed; cases with incomplete information were excluded.The following parameters were collected: sex, age at diagnosis, initial clinical manifestations, number and location of TDLs, presence and pattern of contrast enhancement on MRI, and cerebrospinal fluid oligoclonal bands (OCBs).
Results:
Among 1,228 patients diagnosed with MS according to prevailing criteria, 30 (2.44%) presented TDLs as their first manifestation. Women represented 63% of the cohort, and the median age at onset was 26.5 years (IQR 19.25–35). Clinically, 67% of patients presented multifocal manifestations, with atypical symptoms such as encephalopathy (17%) and seizures (3%) being notable. On MRI, only 10% of patients exhibited a solitary TDL, with supratentorial localization being the most frequent. Contrast enhancement was present in 66% of cases, most commonly showing an incomplete ring pattern. OCBs were positive in 67% of patients
Conclusions:
TDLs are an infrequent presentation of MS, it is associated with atypical clinical features and imagenological findings that can impede correct diagnosis
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