Melanocytic Naevus: Diagnosis, Treatment, and Skin Cancer Prevention

A melanocytic naevus, also known as a mole, is a very common benign skin lesion formed due to a local proliferation of melanocytes. Brown or black melanocytic naevus is often called pigmented naevus because of the presence of melanin.

Melanocytic naevus is classified as either a congenital melanocytic naevus or an acquired naevus. By definition, a congenital melanocytic naevus is present at birth, while an acquired naevus appears later in life.

Everyone has melanocytic naevus. Approximately 1% of the world's population is born with at least one congenital melanocytic naevus. Individuals with fair skin have a higher prevalence of developing more melanocytic naevi in comparison with those who have a darker skin type.

Moles that appear between the ages of 2 and 10 are the most prominent and persistent throughout an individual's life. Melanocytic naevi formed in later childhood and adulthood are usually attributed to sun exposure and may disappear with time.

Melanocytic naevi are diagnosed clinically based on their appearance. The majority of moles are harmless and do not require any treatment. They may only be removed for cosmetic reasons or to exclude the possibility of skin cancer. Moles may also be removed if they are considered a nuisance due to irritation caused by a comb, razor, or clothing.

Moles are considered abnormal if they change in size, structure, shape, or colour. If a new naevus develops after the age of 40 years, it must be assessed by a dermatologist to exclude the possibility of melanoma. If a melanocytic naevus is bleeding, itchy, or crusty, additional examinations must be performed. If ABCD characteristics are present, namely asymmetry, border irregularity, colour variation, and diameter greater than 6 mm, the mole must be assessed by a dermatologist for suspicious features.

Naevi that are considered suspicious for melanoma must be excised for histopathology.

Surgical techniques used for the removal of a naevus include excision biopsy, shave biopsy, laser, and electrosurgery. Excision biopsy is performed on flat or suspicious melanocytic naevus. Shave biopsy is performed on a protruding melanocytic naevus. Laser treatment may be administered to reduce pigmentation or remove coarse hair.

The development of melanocytic naevi can be minimised if conscious sun protection is maintained, particularly when followed from birth. Sun protection helps to reduce skin ageing and the development of skin cancer.

It is advisable to choose fabrics designed for sun exposure with a rating of SPF 50 or higher. Sunscreen must be applied to uncovered areas. Additional recommendations include wearing a hat, long sleeves, a long skirt, or pants.

The majority of moles formed during childhood remain for the rest of an individual's life. Teenagers and young adults have the greatest number of naevi. With age, the number of naevi tends to decline as some moles fade over time.

To increase the likelihood of detecting melanoma in its early stages, a monthly self-skin examination is recommended. If changes in a mole or the formation of a new lesion are observed, a dermatologist should be consulted. Regular skin check-ups with a dermatologist are strongly recommended for patients with atypical-looking naevi, a high number of naevi, or a past history of skin cancer.