Localized skin lesion Capillary malformation 2016-10-28T23:39:18Z There are many different classifications, and some authors treat the term capillary malformation as being synonymous with port wine stain (nevus flammeus). We refer to the detailed classification of Happle (PMID:25864701), which we do not completely follow. A capillary malformation is a flat, sharply defined vascular stain of the skin. It may cover a large surface area or it may be scattered and appear as little islands of color. In a capillary maformation, the predominant vessels are small, slow-flow vessels (i.e., arterioles and postcapillary venules).