Intravascular papillary endothelial hyperplasia (IPEH), also known as Masson tumour, is a rare nonneoplastic vascular lesion caused by the abnormal proliferation of endothelial cells. IPEH presenting as a soft-tissue mass may simulate a sarcomatous tumour clinically and radiographically. We report an infant with IPEH affecting the right calf. The MRI appearance is described, and the literature is briefly reviewed. Knowledge of the MR characteristics of IPEH may facilitate its diagnosis and obviate an invasive procedure.