Sclerosing inflammatory pseudotumor of the urinary bladder in a child.

A case of inflammatory pseudotumor of the urinary bladder in a 2-year-old child is presented. It was characterized by nodular intravesical growth and massive infiltration of the bladder wall. Microscopically, the lesion showed in its largest part a relatively paucicellular spindle cell growth and a sclerotic appearance with a thin superficial cellular zone resembling granulation tissue. Another morphological characteristic was a marked capillary proliferation revealed by immunohistochemical reactions to factor VIII-associated protein, laminin, and collagen IV. The last feature appears to be an integral part of the process, which most closely resembled fibromatosis of the adult type, a rare pattern of growth in inflammatory pseudotumor.