Melanocytic naevi “moles”

Naevus – is the medical term for a birthmark

Melanocytic – “cyte” is the medical term for “cell” and “melanin” is the brown pigment (tan) in the skin.

Written by Dr Mohungoo and Dr Britton, Consultant dermatologists, Myhealthfile.me , 30th April 2020

So: melanocytic naevus means a birthmark from the cells that make pigment in the skin – the melanocytes – we will call them a “mole”


The naevus cells in melanocytic naevi come from melanocytes, which migrate to the epidermis from the neural crest during embryonic development, however the reasons for the development of naevi is unknown.

There are many types of mole, all of which are named where they are found  in the dermis.

The melanocytes (pigment cells) are found at the dermo- epidermal junction – where the two levels of the skin join – the dermis (the lower area of the skin) and the epidermis (the upper layer of the skin that we touch).

So who gets moles or melanocytic naevi?

Melanocytic naevi, or moles are present in most Caucasians, and are less common in Asians and Black Africans. They gradually develop as children from the age of 3 onwards and through teenage years.

If you are worried you can check your mole with a UK trained consultant dermatologist at https://myhealthfile.me

What does a mole or melanocytic naevus look like?

Usually a flat macule (macule is medical term for a flat area of colour change in the skin – usually brown from melanin) with a light to dark brown colour.


Some types of moles can be found on the palms, soles and genitalia - this is not serious in it.

The picture below shows several melanocytic junctional naevi. Some are the same colour throughout whereas some have a different colour within them i.e. a small darker area.

This is normal for some but if the pigment CHANGES then this should be taken seriously.

 

 

 

 

 

 

 

 

 

If you are worried you can check your mole with a UK trained consultant dermatologist at https://myhealthfile.me

Melanocytic naevi – a compound naevus​

The melanocytes in a compound melanocytic naevus are both superficial (high up) and deep in the dermis.

 

 

 

 

 

 

 

 

 

The amount of pigmentation (melanin)  varies and can be found anywhere on the skin and are usually slightly raised

The picture below shows a raised compound naevus.

 

 

 

 

 

 

 

 

 

 

 

 

 



 

 

Melanocytic naevi – intradermal naevus

The melanocytes are deep in the dermis. The naevus is a dome shaped papule or nodule and may be pigmented or skin coloured.
Often found on the face and neck, they can have a deep blue colour giving rise to the name of 'blue naevus'.


If you are worried you can check your mole with a UK trained consultant dermatologist at https://myhealthfile.me

Melanocytic naevi – what happens to them through life
The naevi or moles may be present at birth but many develop and increase in number up to teenage years.
They often become gradually more raised during life and can deepen in colour.During puberty and pregnancy they can become darker in colour and change size. Some people have very many large melanocytic naevi/moles which are irregular in colour, but this is normal for them.

Melanocytic naevi – what happens when they itch and are painful?
Moles can become irritated by clothing, especially bra straps and waistbands. This can lead to them becoming itchy and occasionally bleed. If symptoms persist then you should consult your doctor.

The moles when they become damaged can then be infected, particularly with staphylococcus aureus. If severe enough then treatment may be needed.

This is not necessarily bad (sinister) and does not mean the mole is more likely to become cancerous. However if there is a doubt get a mole check by an expert.

Melanocytic naevi -moles can become cancerous – what to look for
It is the CHANGE in a mole that is what is looked for.
If a mole is CHANGING with any of the following then make a not, even take a photograph of the mole and seek advice.

  • Asymmetry – instead of being symmetrical the mole becomes irregular.

  • Border – irregular: instead of the border of the mole being smooth and well defined the border becomes irregular.

  • Colour – variation: instead of the mole being the same colour throughout and staying that way, if the mole becomes variable in colour with some dark and some light areas in it.

  • Diameter - >6mm

  • Elevation – instead of being smooth, the mole becomes raised and lumpy.

Bleeding and itching and pain in a mole are also signs that need to be taken seriously.

NB: some people have many moles which look like the description above, but that is normal for them.

If you are worried you can check your mole with a UK trained consultant dermatologist at https://myhealthfile.me

Melanocytic naevi – other things on the skin that can look like a mole

Listed below are the other types of skin problem that can look like a simple melanocytic naevus, or mole:

Benign melanocytic naevus

Seborrhoeic wart

Haemangioma

Dermatofibroma

Pigmented basal cell carcinoma

Benign lentigo


The most important diagnosis that can resemble a mole is a malignant melanoma which is the skin cancer from the pigment cells - melanocytes.

If you are worried you can check your mole with a UK trained consultant dermatologist at https://myhealthfile.me

 

 

 

 

 

 

 

 

 





 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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