Intravascular papillary endothelial hyperplasia (Masson's tumor) presenting as a triceps mass.

Intravascular papillary endothelial hyperplasia (IPEH) is a nonneoplastic reactive endothelial proliferation most commonly located in the skin or subcutaneous tissues although it has been reported in multiple locations throughout the body. We present a case of intravascular papillary endothelial hyperplasia presenting as a soft tissue mass in the triceps muscle. IPEH is not well-described in the radiologic literature.