Objective:

To evaluate the demographic, clinical, radiological, and laboratory characteristics, treatments, and clinical outcomes of patients with tumefactive demyelinating lesions (TDLs) observed during the course of demyelinating diseases.

Background:

TDLs are rare inflammatory demyelinating lesions of the central nervous system that measure 2 cm or more in diameter and often mimic neoplastic processes, complicating differential diagnosis.

Design/Methods:

Nineteen patients diagnosed with a central nervous system demyelinating disorder and found to have TDLs on magnetic resonance imaging between December 2022 and December 2024 at Başakşehir Cam and Sakura City Hospital were retrospectively reviewed. Demographic data, lesion characteristics, cerebrospinal fluid (CSF) findings, AQP4-IgG and anti-MOG antibody results, Expanded Disability Status Scale (EDSS) scores, and treatments were analyzed.

Results:

Ten patients (52.6%) were female, and the mean age at disease onset was 31.8 years. In 11 patients (57.8%), TDLs were detected during the first attack. The mean CSF white blood cell count was 8.4/mm³ and pleocytosis (WBC >5/mm³) were present in 36.8%. Oligoclonal bands were positive in 52.6%, while AQP4-IgG and anti-MOG antibodies were negative in all. Sensory symptoms were most common at presentation (63%). Fourteen patients (73.6%) met the 2017 McDonald diagnostic criteria for multiple sclerosis. The mean EDSS was 1.77 at the first attack and 1.61 at follow-up. MRI revealed solitary lesions in 68.4%, most often with a nodular enhancement pattern.

Conclusions:

TDLs were most commonly observed at disease onset and were associated with multiple sclerosis in nearly three-quarters of cases. Despite their tumor-like appearance, characteristic MRI features and CSF findings help differentiation. Larger cohorts with longer follow-up are needed to clarify prognosis and refine diagnostic criteria.