To describe the clinical course, neuroimaging and prognosis of patients with tumefactive demyelinating lesions.

A rare manifestation, tumefactive demyelinating lesions (TDL) are large (≥ 2 cm) demyelinating lesions that pose diagnostic challenges due to their resemblance to other brain pathologies. Meticulous differentiation from neoplastic processes through clinical and radiological features is essential for timely diagnosis and treatment.

We describe the case series of 32 patients (19F, 13M) with clinicoradiologically or histologically diagnosed TDL. In this chart review, clinical course, investigations, neuroimaging, histologic biopsy preparations, treatment and follow up were evaluated and recorded in a pre-designed proforma.

The median age at onset was 29.5 years (range 4-60), with most patients experiencing subacute onset (78.1%) and symptoms lasting from 3 days to 24 weeks (median 5.5 weeks). The clinical features included motor symptoms (84.4%), sensory symptoms (40.6%), headache (31.3%), cognitive symptoms (28.1%), seizures (25%), cortical symptoms (25%), visual disturbances (21.9%), and behavioral symptoms (15%). 12 patients had OCB positivity in CSF, and 2 tested positive for serum MOG. The lesions were predominantly localized in the parietal (87.5%) and frontal lobe (81.3%) with 79.1% showing mass effect, 93.7% edema, and 93.7% various enhancement patterns. Peripheral diffusion restriction was seen in 71% of patients, and MR spectroscopy showed elevated Cho/NAA peaks in all 15 patients tested. After a median follow-up of 18 months (6-148 months), 59.4% presented with relapses with a mean interval between relapses of 11 months (2-84 months). Median EDSS at onset was 4.0 which improved to 1.0 at last follow-up.

Our case series highlights the importance of clinical evaluation and neuroimaging in differentiating TDL from other pathologies. Most patients showed marked improvement with appropriate treatment, although a considerable proportion experienced relapses. Early recognition and tailored management are essential to improving outcomes, with follow-up showing a significant reduction in disability over time.