Classification is by:
(1) type of defect
(2) form and subform
Types of defects:
(1) predominantly arterial
(2) predominantly venous
(3) predominantly lymphatic
(4) predominantly arteriovenous shunting or fistulae
(5) combined or mixed vascular defects
Forms:
(A) truncular = embryonal dysplasia of differentiated vascular trunks
(A1) aplasia or obstructive (for Types 1 to 3) - aplasia, hypoplasia or stenosis
(A2) dilatation (for Types 1 to 3) - ectasia, as aneurysm (dolichomegaarteria), phlebectasia or lymphangiectasia
(A3) deep (for Type 4) - with or without aneurysms
(A4) superficial (for Type 4)
(A5) arterial and venous (for Type 5) - without arteriovenous shunt
(A6) hemolymphatic (for Type 5) - with or without arteriovenous shunt
(B) extratruncular = remnants of primitive capillary networks
(B1) infiltrating - diffuse, with or without arteriovenous shunts
(B2) limited - localized, with or without arteriovenous shunts (without - cavernous spaces)
