More information: What are AVMs?
Medicine distinguishes between vascular tumours (haemangiomas) and pathological vessel connections (vascular malformations) (Table 1). The differences between haemangiomas and vascular malformations are summarised in Table 1. There are also mixed forms, which makes a standardised approach to such lesions difficult.
Differences between haemangiomas and vascular malformations (from 4)
|Special characteristics||Exhibits cellular proliferation||Made up of dysplastic vessels|
|Development||Small or absent at birth||Already present at birth|
|Growth||Rapid growth during early childhood||Growth proportional to the patient’s growth|
|Resolution||Involution / resolution during late childhood||No regression / resolution|
Vascular malformations are defects in the vessels’ embryonic development and are always present at birth, although they may not necessarily be visible or symptomatic. The malformations can arise from the arterial, capillary, venous or lymphatic vascular system (Table 2). With regard to the fluid velocity in the abnormal vascular connections, vascular malformations are classified into two groups: Malformations with fast blood flow (high-flow) and malformations with slow blood flow (low-flow) (Table 3).
Simplified ISSVA classification of vascular anomalies
|Vascular tumour||Vascular malformations|
|Haemangioendothelioma angioma||Arterial / arterio-venous malformation (AVM)||Capillary-arterio-venous||Fast|
Classification into high-flow and low-flow malformations according to Burrows & Mulliken 1983 (7)
|Definition||Connection to the arterial or capillary vascular system||Connection to the venous or lymphatic vascular system|
High-flow malformations have a connection to the arterial or capillary blood vessel system, whereas low-flow malformations have connections to the venous or lymphatic vascular system (Figure 1).