Mimics of brain tumor on neuroimaging: part I

Brain tumor is a distinct pathological entity that differs from other diseases, including cerebrovascular, demyelinating, inflammatory, infectious, and various miscellaneous diseases. Insidious onset and gradual progression of signs and symptoms are common in patients with brain tumors, whereas the onset of cerebrovascular diseases is usually acute or sudden. Patients with demyelinating, inflammatory, or infectious diseases show subacute onset. Differentiation of brain tumors from other disorders is usually possible from the clinically and radiologically characteristic features. However, in some diseases other than brain tumors, an atypical clinical course and/or radiological findings may suggest or simulate those of brain tumors. The diagnosis of brain tumor is confirmed histopathologically, and appropriate therapies are given to the patient based on the histopathological type and grade of the tumor. In order to obtain a specimen for histopathological examination, surgical intervention is required. Other diseases are usually diagnosed clinically and radiologically. Invasive procedures should be avoided in making a diagnosis. Therefore, differentiation of brain tumors from other diseases is a critical issue for neuroimaging. Detailed inspection of images is necessary, and characteristic findings, and additional imaging methods, such as diffusion-weighted imaging, are often helpful for the differential diagnosis. We assess the imaging findings of diseases simulating brain tumors and review the literature.