Congenital Agenesis of the Internal Jugular Vein: An Extremely Rare Anomaly

Table 1

ISSVA classification of vascular anomalies.

Tumors	Malformations
Hemangioma; Hemangioendothelioma; Angiosarcoma; Miscellaneous	Slow-flow
	Capillary
	Lymphatic
	Venous
	Fast-flow
	Arterial
	Combined