RESUMO
BACKGROUND: Demyelinating diseases can present as space occupying lesions with in the brain. It is clinically and radiologically difficult to differentiate them from primary neoplasms. Histopathologically they mimic astrocytic neoplasms closely and identifying these lesions correctly has a profound impact in treatment and prognosis of these patients. AIMS AND OBJECTIVES: The objective was to determine the histopathologic features of such acute focal demyelinating disease that clinically presented as brain tumors. MATERIAL AND METHODS: Seven cases were included for the study. Detailed histopathological examination including stains for myelin and axon were performed. The histopathological keys in arriving at the right diagnoses included a well demarcated lesion that contains uniform distribution of foamy macrophages in the absence of any associated coagulative necrosis, sheets of gemistocytic astrocytes in the white matter that show well-formed processes, perivascular chronic inflammatory cell infiltration and total absence of myelin with relative preservation of axons within these areas. CONCLUSION: The degree of suspicion (clinical, radiological and histopathological) should be high to diagnose these group of lesions. The above-mentioned diagnostic keys should help in arriving at the correct histopathological diagnoses of such cases.