What is a mole?

What is a mole?

Those pale or coloured raised or flat lesions on our body could be what we call moles. So what are they? Moles (or naevus) are collections of skin cells that have grown together. Depending on the level where they originated in the skin determines the colour and hence the appearance of the mole. Most moles are coloured, and this is a result of a specific pigment producing cell (melanocyte). These cells are responsible for producing the pigment in our skin and hence decide our overall skin colour (as well as the colour of our moles).

Moles develop for various reasons, but commonly its related to sun exposure, genetics, hormonal influences (pregnancy and puberty), ageing. It is more common for fair skin individuals to have more moles than darker individuals. And it is not unusual for fairer skin individuals to have anywhere from 10-50 moles on average scattered over their body. And it is normal to develop more moles as you age and expose your skin to ultraviolet radiation (sun exposure).

So what type of mole do I have?

Well there are multiple descriptions to identify various moles:

Common Vs Atypical Mole

A common mole is a well rounded pigmented raised mole that is usually on sun exposed skin, and rarely develops skin cancer. This is in contrast to Atypical moles. These moles can be raised or flat or combination of this. They have irregular border, and irregular colour (“variegated”). Tend to be larger than other moles. While most dysplastic naevi are actually benign, they have an increased chance of turning malignant, and hence need regular skin monitoring (at least yearly).

Congenital Vs Acquired Moles

Congenital moles are moles that appear in your 1st year of life and develop either in the top part of the skin (epidermis) or mid level of the skin (dermis), containing melanocytes (pigment producing cells). They tend to have hair growing from them also. They need to be monitored as they have a small risk of developing skin cancer over one’s lifetime.

Acquired moles are usually benign lesions that develop in childhood or adulthood and are usually related to sun exposure. They have a small risk of changing to malignant lesions.

Junctional Naevi

This category of mole is usually the most coloured moles we see as they develop from the lower layer of the epidermis where the melanocytes (pigment producing cells of the body/skin) reside – the “basal layer” of the epidermis.
Junctional naevi are an accumulation of melanocytes at the junction of the epidermis and dermis (layer of skin beneath the epidermis). They are usually raised dark regular looking moles. But their pigmentation can vary from a tan/fawn colour to dark brown. They usually occur in younger ages (childhood and early adulthood).

Intradermal Naevi

These moles are usually lighter coloured moles, and outer skin coloured. Their lighter colour appearance is related to the site of where the accumulation of melanocytes reside, which is in the dermis. They are very common moles and usually benign and occur in childhood and throughout adulthood.

Compound Naevi

Are moles that exhibit features of both Junctional and Intradermal naevi. They usually have a central raised portion and surrounding flat areas. They have distinct borders and regular colour.

Unna Naevi

These moles are derived from the dermis of the skin and tend to have a unique surface that is bumpy and takes the shape of a small raspberry.

Halo Naevi

These moles have a pale surrounding to a central raised pigmented segment. It is believed the body’s immune system has attacked the pigment cells surrounding the raised central component. The aetiology of this phenomenon is still not known, but these moles tend to be benign.

Blue Naevi

Some moles appear “blue” in colour. This is related to the pigment in the mole residing deep in the dermis of the skin.