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Background: Lymphocytic vasculitis of the central nervous system is an uncommon subtype of primary angiitis of the central nervous system (PACNS) - a rare inflammatory disorder affecting parenchymal and leptomeningeal arteries and veins. Case Report: Establishing diagnosis on the basis of neuroimaging only is difficult, as it can mimic a brain tumor. Thus, histological diagnosis is essential for appropriate management. We present a case of biopsy-proven lymphocytic vasculitis mimicking a brain tumor on neuroimaging that was subsequently successfully treated with steroid therapy. We also discuss the findings in perfusion MR (PWI) and MR spectroscopy (MRS). Conclusions: Regional hypoperfusion on PWI and elevation of glutamate and glutamine levels on MRS (without associated typical tumor spectra) are common findings in inflammatory disorders, including PACNS, and can be useful in differential diagnosis with tumors.