The Sturge-Weber syndrome consists of a large facial nevus flammeus in the distribution of the ophthalmologic division of the trigeminal nerve accompanied by ipsilateral leptomeningeal angiomatosis. Usually, when angiomatous nodules develop in a nevus flammeus of a patient with Sturge-Weber syndrome they are pyogenic granulomas. We describe an acral arteriovenous tumor developed within the nevus flammeus of a patient with Sturge-Weber syndrome. To our knowledge, acral arteriovenous tumor has not been previously described in the cutaneous vascular malformation of patients with Sturge-Weber syndrome. The development of acral arteriovenous tumor within the vascular malformation of a nevus flammeus in this patient with Sturge-Weber syndrome probably results from a vascular proliferation secondary to underlying arteriovenous shunts.