Tumefactive Multiple Sclerosis presenting as Acute Ischemic Stroke.

Background And Purpose: Multiple sclerosis (MS) plaques appear as well-demarcated, homogenous small ovoid lesions on magnetic resonance imaging (MRI). Atypical radiographic features of MS lesions include size greater than 2 cm, mass effect, and edema. Tumefactive MS lesions can radiographically mimic intra-cranial neoplasms, infarction, as well as infections. In atypical cases of tumefactive demyelinating lesions, brain biopsy may be required for the diagnosis.

Methods: The authors describe the case of a 43 year old woman who presented with worsening right-gaze preference and left side weakness and was initially diagnosed with acute ischemic stroke. The patient underwent laboratory investigation and brain contrast-enhanced MRI before undergoing brain biopsy.

Results: Fluid attenuation inversion recovery (FLAIR) MRI showed an increase in signal intensity in the right frontal lobe sub-cortical region. Diffusion-weighted imaging showed an area of restricted diffusion involving the white matter of the right-frontal lobe. Cerebrospinal fluid studies were normal except for the presence of oligo-clonal bands. Magnetic resonance spectroscopy (MRS) demonstrated an elevated choline (Cho)/creatine ratio, increase lactate, and normal N-acetylaspartate (NAA)/creatine ratio, findings suggestive of an inflammatory or a demyelinating disease. A brain biopsy of the right frontal lesion was performed and revealed well-demarcated foci of demyelination with axonal preservation. Peri-vascular and parenchymal CD3(+) T-cells were also identified within the demyelinated foci, findings that further supported the diagnosis of active multiple sclerosis.

Conclusion: Tumefactive MS can be radiographically misdiagnosed as one of several conditions, among which are infarction, infections, and tumors. Brain biopsy may be needed for diagnosing challenging cases of tumefactive MS.