- Nevus Flammeus is a non-neoplastic ectasia, or localized dilation of pre-existing blood vessels, which primarily occurs in the skin, specifically in the dermis of the head and neck. These lesions are often present at birth and are thus considered "Birth Marks". They are not of clinical concern and in most cases regresses with age. In some cases the lesion may grow with the child and are thus known as "Port Wine Stains". In such cases the concomitant presence of Sturge-Weber Syndrome should be investigated.