a. Colour
The colour of CMN can change over time. CMN at birth are often black, or even dark purple/red. They are usually at their darkest at birth, with the exception of the very rare tardive CMN. Over the first few years the colour will settle to its more permanent colour, in the same way that the child’s hair and eyes can change in the first few years after birth. The final colour of CMN after a few years is related to the background skin colour of the individuals, usually some sort of shade of brown to black, but sometimes they can be more reddish in colour, particularly in individuals with red hair. People with lighter skin and hair colours therefore usually get more lightening of their CMN after birth than people with darker skin and hair colours. In addition, the colour is often very mixed inside the CMN, with smaller areas of different colour on a background colour.
b. Hairiness
CMN often have hair growing out of them. This hairiness is often not visible at birth but can develop over time. Hairs on CMN are a bit different from hair on the rest of the skin. They grow longer, they are usually darker and are often more coarse. Sometimes they’re lighter, which is rare. If a CMN is on the scalp there is usually more luxuriant hair growth over the lesion and the hair grows faster than on the rest of the scalp. Occasionally, CMN are completely hairless, even ones that occur in the scalp, or they can have patchy hair loss or hairs without pigment (like grey hair). Hair can become white or grey before the rest of the hair, this can happen in childhood and as people get older it can happen more.
Many people tend to shave the hair overlying CMN, and for this we would recommend using an electric shaver or beard trimmer rather than a wet shave with a blade. Shaving CMN hair does not make the hair grow back thicker or darker over time.
In theory hair on CMN could be chemically coloured if people want to dye the hair on their head and have a CMN on the scalp. We would suggest that it would not be coloured directly on to the CMN, so avoiding direct scalp application so as not to irritate the skin. We would advise you to inform your hairdresser as they should have other methods to avoid the colour touching the CMN too much.
You may also want to read the section Questions about Treatment.
c. Texture
The texture of large CMN tends to be different from that of normal skin, often being softer, looser and more wrinkled. However this is variable and the CMN can be nearly flat or can be very folded or lumpy.
d. Spontaneous lightening of CMN
In most children the CMN will lighten to some degree in the first few years of life. This is still being studied but it appears to be more prevalent in children with light or red hair and pale skin than in those with darker hair and skin colour. In some children the lightening is very dramatic and in very rare cases the CMN can disappear or stop producing pigment.
You may also want to read the section Questions about Treatment.
