RESUMO
Low-grade gliomas are uncommon primary brain tumours, located more often in the posterior fossa, optic pathway, and brain stem and less commonly in the cerebral hemispheres. Two patients with diagnosed recurrent cystic pilocytic astrocytoma critically located within the brain [thalamic and brain stem] were treated with gamma knife surgery. Gamma knife surgery did improve the patient's clinical condition very much which remained stable later on. Progressive reduction on the magnetic resonance imaging studies of the solid part of the tumour and almost disappearance of the cystic component was achieved within the follow-up period of 36 months in the first case with the thalamic located lesion, and 22 months in the second case with the brain stem located lesion. Gamma knife surgery represents an alternate tool in the treatment of recurrent and/or small postoperative residual pilocytic astrocytoma especially located