A 'Mongolian spot' is a term given to a slate - blue patch of skin discolouration, usually across the lower back and bottom (and occasionally the tummy) of darker skinned babies. The area can look like a bruise and is caused by an accumulation of pigment under the baby's skin. Mongolian spots are usually present at birth, or appear a few hours, or days, afterwards. Occasionally, it can become noticeable as late as 3 months of age. Mongolian spots are harmless and will fade away naturally within the first 3 years.
Image 10-34 shows a baby with a Mongolian spot on the top of his left buttock.
The traditionally recognised 'birthmarks' are medically known as brown, pigmented 'naevi'. They can appear in a variety of shapes and sizes and will usually stay with the baby for life, but not cause any problems.
Some birthmarks are flat and pale, or 'coffee-coloured' enlarging, as the baby grows older, but not becoming darker. Others are dark and slightly raised, sometimes with hair growing out of them, often called a mole. Occasionally these marks do not become apparent until the baby is a couple of months old. If you are concerned about the mark on your baby you can consult with a dermatologist (or skin specialist).
'Port Wine' mark.
A port wine 'stain' or mark is a birthmark caused by dilated capillaries in the skin, appearing bright red to purple in colour. Port wine marks tend to appear more so on the face and neck but can be anywhere on the body.
The mark itself is usually different in texture with the stain having defined edges. They are a permanent mark on your baby and can be upsetting if on a sensitive area such as the baby's face. There are some laser treatments available to remove port wine stains, usually when the child is older. You may wish to discuss this option with a Paediatrician or Dermatologist, taking into consideration the possible discomfort, procedures involved the success rate with these interventions.