Most of the acute tumefactive demyelinating lesions(TDLs) are enhancing with gadolinium on MRI. Here we report two unique cases of acute symptomatic non-enhancing TDLs.

Tumefactive multiple sclerosis is a rare form of demyelination, typically presenting as large lesions (>2cm) with associated vasogenic edema that can mimic tumors.

First case is a 34 year-old female admitted with right sided weakness and numbness for two days. She had mild transient left sided weakness two months prior to admission that resolved spontaneously. MRI showed diffusion restriction in the left parietal region and increased FLAIR signal in the right frontal and occipital regions. Workup revealed elevated CSF oligoclonal bands(OCB) and myelin basic protein(MBP) in addition to abnormal right eye visual evoked potential.

Second case is a 22 year-old female admitted with three days of progressive right sided weakness. MRI showed large right frontoparietal lesion, abnormal diffusion and no gadolinium enhancement. Workup showed elevated CSF MBP and OCB.

The two patients had a similar clinical course, and their symptoms improved rapidly with 5 days of intravenous steroids. Repeat MRI showed resolution of the mass effect; however, both patients’ symptoms recurred in one month, and plasmapharesis was initiated after which MRI improved with no recurrence of symptoms.