Serious renal hemorrhage in Masson tumor

Intravascular papillary endothelial hyperplasia (IPEH; Masson tumor) is a vascular lesion of blood vessels, first described in 1923 by Masson, who termed it "hemangioendotheliome vegetant Intravasculaire." This lesion consists of an exuberant, usually intravascular, proliferation of normal endothelial cells and is considered to be a reactive vascular proliferation after traumatic vascular stasis. The disease frequently occurs in skin and subcutaneous tissue; occurrence in solid organs is rare. We report a rare case IPEH that recurred as a possible consequence of an acute hypertensive arterial crisis in a patient with chronic kidney failure after kidney transplantectomy. Thirty days after transplantectomy, a 49-year-old white man receiving hemodialysis had pain in the left abdominal flank and acute anemia with serious hypovolemia after a hypertensive arterial crisis. An emergency non-contrast enhanced abdominal computed tomographic scan showed a massive retroperitoneal hemorrhage. A left nephrectomy was performed for evidence of a native kidney breach with toilette of the abdominal cavity. Histologic analysis revealed that the renal lesion had several important distinguishing characteristics that confirmed the diagnosis of IPEH. This lesion is considered to be an usual form of thrombus organization that is marked by excessive papillary endothelial proliferation. In rare cases, it is present in a solid organ of the abdominal cavity especially the kidney. Intravascular papillary endothelial hyperplasia is a benign lesion but can be dangerous. Clinical, radiologic, and histologic diagnosis of IPEH is difficult.