Nasopharyngeal Capillary Arteriovenous Malformation with Ancient/Symplastic Change: A Simulator of Malignancy.

There are only 8 published cases of symplastic hemangioma (SH), a relatively recently described, distinct benign entity characterized by pleomorphic vascular smooth muscle and interstitial cells in a pre-existing, long-standing vascular lesion. Seven of these cases were of SH in cutaneous locations, and 1 case was described in the mediastinum. We report the case of the 12-year-old girl with a nasopharyngeal tumor mass with prominent symplastic changes arising in the background of a combined capillary arteriovenous malformation. After critical analysis of all published cases of SH, it is clear that these lesions commonly represent capillary arteriovenous malformations (CAVM) with ancient/symplastic changes according to current terminology proposed in the classification required by the International Society for the Study of Vascular Anomalies (ISSVA). This is the first such lesion reported in a mucosal location and presenting in the pediatric age group. CAVM with ancient/symplastic change follows a benign clinical course, but it can simulate a malignant vascular tumor.