Intravascular papillary endothelial hyperplasia of the bladder: Case report and review of the literature.

Intravascular papillary endothelial hyperplasia (IPEH), also known as Masson's tumor, is a benign unusual vascular lesion thought to arise from an organizing thrombus. Histologically, IPEH is characterized by papillary fronds lined by proliferating endothelium that may mimic angiosarcoma, and therefore the correct diagnosis may prevent unnecessary radical procedures. Involvement of the bladder is extremely rare, with only three cases reported in the literature. We report a case of IPEH arising in the bladder of a patient with history of prostate cancer treated with radiotherapy.