Capillary malformation

What it means

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).

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.

Rare diseases that can present with this9

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category