Introduction: We report three cases of demyelinating disease with tumor-like presentation. This information is particularly important to both neurosurgeons and neurologists who should be aware that inflammatory demyelinating diseases can present as a mass lesion, which is indistinguishable from a tumor, both clinically and radiologically, especially when there is no evidence of temporal dissemination of this disease.

Case presentation:
The first patient was a 42-year-old Malay woman who developed subacute onset of progressive quadriparesis with urinary incontinence. Magnetic resonance imaging of her spine showed an intramedullary lesion at the C5-C7 level. She was operated on and biopsy was suggestive of a demyelinating disease. Retrospective history discovered two episodes of acute onset of neurological deficits with partial recovery and magnetic resonance imaging of her brain revealed demyelinating plaques in the centrum semiovale.

The second patient was a 16-year-old Malay boy who presented with symptoms of raised intracranial pressure. A computed tomography brain scan revealed obstructive hydrocephalus with a lesion adjacent to the fourth ventricle. An external ventricular drainage was inserted. Subsequently, a stereotactic biopsy was taken and histopathology was reported as demyelination. Retrospective history revealed similar episodes with full recovery in between episodes.

The third case was a 28-year-old Malay man who presented with acute bilateral visual loss and confusion. Magnetic resonance imaging of his brain showed a large mass lesion in the right temporoparietal region. Biopsy was consistent with demyelinating disease. Reexamination of the patient revealed bilateral papillitis and not papilledema. Visual evoked potential was prolonged bilaterally. In all three cases, lumbar puncture for cerebrospinal fluid study was not carried out due to lack of patient consent.

Conclusions:
These cases illustrate the importance of considering a demyelinating disease in the differential diagnosis of a mass lesion. Critical analyses of clinical presentations coupled with good physical examination are vital in assisting clinicians to reach the correct diagnosis.