Plunging arteriovenous malformation in the floor of the mouth: a case report.

An arteriovenous malformation (AVM) is composed of abnormal communications between arteries and veins without the normal intervening capillary bed. An 11-year-old male presented with a painless, doughy submandibular mass. Surgical excision was performed through an intraoral approach; the mass and the surgical field, did not exhibit any significant intraoperative bleeding typical of vascular lesions. Histopathological examination of the specimen revealed a diagnosis of an AVM, with the presence of organizing thrombi within arteries and veins. These abundant thrombi, previously unreported in the arterial part, may explain the negligible intraoperative bleeding.