[Pseudotumors of the central nervous system]

The histopathological differentiation of the pseudoneoplastic lesions from the tumors of the central nervous system (CNS) is not easy in a proportion of cases and the risk of diagnostic misinterpretation in biopsies of the CNS remains relatively high. Here we discuss selected CNS lesions, which can be easily mistaken for a tumor, particularly in the absence of relevant clinical and neuroradiological data - gliosis, tumefactive demyelination, radionecrosis and focal cortical dysplasia. With the exception of the recently available IDH1 immunohistochemistry, there is a lack of simple and reliable histochemical or molecular markers which could facilitate this differential diagnosis. To avoid a diagnostic error, pathologists have to rely on careful microscopic analysis along with its correlation with clinical data and neuroradiological findings.