Pseudosarcoma of the urinary bladder.

A case of pseudosarcoma of the urinary bladder is described in a woman aged 23. The tumor presenting with symptoms of cystitis arised in the left wall and invaded vesical cavity and pelvis. Histological, histochemical, immunohistochemical and electron microscope studies revealed a fibroblastic and myofibroblastic proliferation with atypias, accompanied by inflammatory infiltrates and rich vascularity. The tumor was furthermore characterized by extensive necrosis, involving the muscularis propria, and infiltrated the perivesical fat. The favourable outcome four years after partial cystectomy suggests the diagnosis of pseudosarcoma. The differential diagnosis and the pathogenesis of this rare lesion is discussed.