Pseudosarcomatous tumour of the bladder is a benign neoforming process of uncommon occurrence, consisting in a fibroblastic proliferation originated in the vesical wall and the perivesical fat, with unknown etiology, that given its cellular pleomorphism and the infiltrative nature of the injury can be incorrectly diagnosed as a sarcoma. This paper presents one case of pseudosarcomatous tumour of the bladder in a 9 year-old child, with no history of local traumatism or previous surgery, consisting in a tumoration affecting the vesical wall associated with a significant perivesical fibrosis with extension towards the area of the iliac veasels. Microscopically, the injury shows proliferation of spindle cells, arranged in a myxoid stroma with a prominent vascular net. No cytologic atypia is demonstrated or increase in the number of mitosis. The immunohistochemical study shows features of myofibroblasts in the proliferant cell. A review of the literature is made on 40 cases of inflammatory pseudosarcoma, evaluating the clinical characteristics, morphologic findings and treatment involved, as well as the postoperative evolution of the patient.