Although these disorders are not physically debilitating, they are often associated with psychosocial complications such as anger, depression and frustration, which negatively impact patient’s quality of life. Skin pigmentation tends to be darker in equatorial and tropical regions (Sub-Saharan Africa, South Asia, Australia and Melanesia) where ultraviolet (UV) levels are higher than in regions distant to the equator.4 Classification of pigmentary disorders Pigmentary disorders can be classified as either hypopigmentation (inadequate melanin production or ineffective transport of melanosomes), or hyperpigmentation (overproduction of melanin, distribution, or transport.)2
Melanin is the natural polymer pigment responsible for skin, hair, and eyes colour. It also provides photo-protection of the skin against ultraviolet (UV) radiation. Melanin is produced inside the specialised organelles, melanosomes of melanocytes through a complex process called melanogenesis.3
Hypo- versus hyperpigmentation
Hypopigmentation disorders include conditions such as vitiligo, pityriasis alba and tinea versicolor. Common hyperpigmentation etiologies include melasma, post-inflammatory hyperpigmentation (PIH), solar lentigines, acanthosis nigricans, medication-induced hyperpigmentation, lichen planus pigmentosus, exogenous ochronosis, erythema dyschromicum perstans (Ashy dermatosis), macular amyloidosis and Addison’s disease.2
Hyperpigmentation may be localised, as in the case of PIH or melasma (eg sun exposed skin), or more diffuse in its presentation. Diffuse hyperpigmentation tends to be associated with metabolic causes, certain medications, malignancy or autoimmune and infectious etiologies.7
Melasma is one of the most common forms of hyperpigmentation affecting millions of people worldwide and at least 90% of those are females.7 Melasma comes from the Greek word ‘melas’, which means ‘black’. It presents as brown or greyish patches of pigmentation. It usually appears on the face but can also affect other areas of the body exposed to the sun, such as the forearms and neck.3 The cause of melasma is not clear, but exposure to UV radiation (especially UVA), heat, and visible light all appear to play roles, as do female hormones.
Melasma becomes particularly evident during pregnancy (when up to 50% of women may be affected) and is often referred to as the ‘pregnancy mask’, in people with darker skin and those who tan quickly. It usually becomes more noticeable in summer and improves during the winter months. It is not cancerous and will not develop into skin cancer.3
The use of hormonal drugs such as birth control pills and hormone replacement as well as some anti-epileptic agents have been implicated in the development of melasma. In addition, exposure to UV light from the sun and the use of sunbeds or phototherapy can trigger melasma or make it worse.3 On the basis of location of melanin, melasma can be differentiated into:
» Epidermal: Pigment is brown, and borders are well defined
» Dermal: Pigment is grey brown, and borders are scantily defined
» Mixed: Melanin in both epidermis and dermis
» Indeterminate types: When it is not easy to classify even with the aid of Wood’s light.
South Africa has one of the highest monitored UV levels in the world and protecting the skin against harmful rays is therefore the cornerstone of prevention. As mentioned already, studies show that light from both UV and visible spectrum can induce pigmentation. Both UVA and UVB cause increased melanin synthesis resulting in delayed tanning.6 The skin reacts to an excess of UVB by synthesising melanin pigments and accelerating the thickening of the stratum corneum to increase its protective capacity.
UVA rays can also cause rapid temporary pigmentation, as a result of the oxidation of the melanin that is already present in the epidermis.6 Preventative measures include sun avoidance and sun protection. Sun protection modifying outdoor behaviour (avoiding peak solar radiation between 10:00 and 14:00), using a broad-spectrum UVA/UVB sunscreen with SPF 30 or higher and long-acting broadband UVA protection.6
Because we are exposed to damaging doses of UV – not only when we are on the beach but also through glass windows, sunscreen must be worn at all times, even when indoors. When out in the sun, wearing protective clothing such as a hat (7cm wide brim provides the best facial protection) is highly recommended.6
- Dlova NC, Akintilo LO, Taylor SC et al. Prevalence of pigmentary disorders: A cross-sectional study in public hospitals in Durban, South Africa. International Journal of Women’s Dermatology, 2019.
- Fistarol SK and Itin PH. Disorders of Pigmentation. Journal of the German Society of Dermatology, 2010.
- Pavreen N, Ali AS and Ali AA. On the Intricacies of Facial Hyperpigmentation and the Use of Herbal Ingredients as a Boon for Its Treatment: Cosmeceutical Significance, Current Challenges and Future Perspectives. Intech Open, 2019.
- Del Bino S, Dival C and Bernerd F. Clinical and Biological Characterization of Skin Pigmentation Diversity and Its Consequences on UV Impact. International Journal of Molecular Sciences Review, 2018.
- Plensdorf S, Livieratos and Dada N. Pigmentation Disorders: Diagnosis and Management. Am Fam Physician, 2017.
- Dover JS, Abumann L, Bikowksi J et al. A Stepwise Approach to Melasma Management and Treatment. Cosmetic Dermatology, 2018.
- Desai SR. Hyperpigmentation Therapy: A Review. The Journal of Clinical and Aesthetic Dermatology, 2018