Monofocal large inflammatory demyelinating lesion, mimicking brain glioma.

Here we report two cases of pathologically confirmed tumor-like demyelinating lesions. In comparison with common primary demyelinating diseases, our cases demonstrated atypical radiologic features, such as a large monofocal lesion with mild brain edema, and open ring-like or focal enhancement on magnetic resonance images, suggesting brain tumors. The clinical manifestations included focal neurologic signs due to the lesions, monophasic episodes without relapse over a long follow-up period, and efficacy of oral corticosteroid therapy. Histological analysis of brain biopsy specimens showed the inflammatory demyelination and preserved axons without tumor cells. The present cases suggest the importance of considering inflammatory demyelinating disease in the different diagnosis of monofocal tumor-like lesion.