Strawberry naevus. A strawberry naevus (also known as a cavernous haemangioma or strawberry mark) on the forehead of a baby. This dark-red, raised birthmark is caused by an abnormal distribution of blood vessels. Strawberry marks usually enlarge rapidly during the first few weeks after birth, causing distress but doing little harm. After the age of about six months the lump subsides. About half of all strawberry marks will have disappeared by age five and most by age nine. Strawberry marks that cause problems, such as persistent bleeding or distress, can be removed by freezing or laser treatment.