Ⅰ型:动静脉直接沟通。Ⅱa型:多条动脉或小动脉通过典型的病灶巢与引流静脉相连接;Ⅱb型:与Ⅱa型类似,不同之处在于缺乏病灶巢,代之以单独的瘤样静脉引流通道。Ⅲa型:多条供血动脉流入单一的瘤样扩张性引流静脉,病灶巢位于静脉壁;Ⅲb型:多条供血动脉流入多条扩张性引流静脉。Ⅳ型:浸润型,多条动脉或微动脉不断分支,形成众多的细小动静脉瘘,局部弥散影响周围组织。在多发的小瘘口中,也存在毛细血 Type Ⅰ: arteriovenous direct communication. Ⅱ a type: a number of arteries or arterioles through the typical lesion nest with the drainage veins connected; Ⅱ b type: and type Ⅱ a similar to the difference is the lack of lesion nest, replaced by a separate tumor-like venous drainage channels. Ⅲ a type: a number of feeding arteries into a single tumor-like dilative drainage veins, the lesion nest located in the vein wall; Ⅲ b type: a number of feeding arteries into the number of dilative drainage veins. Type IV: infiltration, multiple arterial or arteriolar branches continue to form a large number of small arteriovenous fistula, the local dispersion of the surrounding tissue. In the multiple small fistula, there are also capillaries