RESUMO
BACKGROUND: Even though numerous theories have speculated either on the vascular or fibrous tumour component as tissue of origin, aetiology of angiofibroma still remain unclear. Histological investigations recently led Beham and coworkers to the assumption that angiofibromas have to be considered as vascular malformations. METHODS: After giving a literature review of the various theories on tumour origin the proposal to consider angiofibromas as vascular malformations is discussed on an embryological base. Taking typical clinical features of the tumour and knowledge of vasculogenesis into account a new explanation for origin of the vascular tumour component is presented. RESULTS: The vascular component of angiofibromas can be explained embryologically due to incomplete regression of the first branchial arch artery (vascular atavism). This vessel arises regularly between embryological day 22 and 24 and recedes during regular development completely until delivery via temporary formation of a vascular plexus. In the late stages of embryological development remnants of the plexus are found at the area of the sphenopalatine foramen, the typical site of angiofibroma origin. Incomplete regression of the vascular plexus of the former first branchial arch artery may form the vascular component of an angiofibroma arising due to growth stimulation at the time of adolescents. CONCLUSIONS: Incomplete regression of the first branchial arch artery presenting an atavism is suited to explain the vascular tumour component of angiofibromas considering main tumour characteristics (origin in the posterior nasal cavity close to the sphenopalatine foramen, main blood supply from the maxillary artery with possible feeders arising from the internal carotid artery). Our embryological contributions support to define angiofibromas as vascular malformations.