RESUMEN
OBJECTIVE: To establish the frequency and nature of space occupying lesions of the central nervous system (CNS) that mimic neoplastic growths. PATIENTS AND METHODS: We reviewed the clinical records, imaging and neuropathological studies of patients operated in different hospitals of Maracaibo, Venezuela during the period January 1 1996 July 31 2002. These patients had a pre operative diagnosis of CNS tumor, and their definitive diagnosis was non neoplastic disease. RESULTS: The 33 cases of expansive, non neoplastic growths represented 8% of 408 CNS lesions diagnosed during the study period. Approximately two thirds of the cases (63,36%) consisted of either inflammatory or vascular lesions, whereas the rest of the cases grouped miscellaneous conditions. CONCLUSIONS: Even though it is not frequent that non neoplastic lesions of the CNS mimic expansive growths of neoplastic nature, on occasions the clinical and neuroimaging features of both groups of entities are remarkably similar.