SummaryThe authors report the case of a cystic cerebellar abcess, treated by radical surgical removal. A spectacular disappearance of all symptoms followed within 48 hours.The authors emphasize the importance of perifocal edematous reactions in cases of posterior fossa abcess. This edema entails most often a fatal issue, before encapsulation could possibly take place. According to the authors, the diffuse aspect of the lesion can be ascribed partly to its position.The actual use of antibiotics in unquestionably favourable to the encapsulation of these spontaneously diffuse lesions.