Melasma

Melasma is a common skin condition that causes dark, discoloured patches to appear on the face. These patches are typically brown to grey-brown and most often show up on the cheeks, chin, nose bridge, forehead, and above the upper lip. Melasma is more common in women than men and often occurs during pregnancy. Additionally, women who take birth control pills or hormone therapies are also more likely to develop melasma.

Causes of Melasma (Aetiology)

Melasma can be triggered by a variety of factors. These include genetic predispositions, exposure to ultraviolet (UV) radiation, pregnancy, hormonal therapies, certain cosmetics, phototoxic drugs, and antiseizure medications. Hormones like oestrogen and progesterone can make melasma worse, particularly when the skin is exposed to the sun. Here’s a closer look at some of these factors:

Genetic Factors

Genetics play a significant role in the development of melasma. It is more prevalent in women and individuals with light-brown skin who live in regions with high sun exposure. About 50% of people with melasma have a family history of the condition, and identical twins can both develop melasma. This suggests that if a close family member has melasma, you are more likely to get it too.

Sunlight Exposure

One of the most significant triggers for melasma is exposure to sunlight. UV radiation from the sun can damage the cellular membranes of skin cells, creating free radicals. These free radicals stimulate melanocytes, which are the cells in the skin responsible for producing melanin, the pigment that gives skin its colour. When melanocytes produce too much melanin, it leads to the dark patches characteristic of melasma. Sunscreens that block UV-B radiation (290-320 nm) do not block longer wavelengths of UV-A and visible radiation (320-700 nm), which can also stimulate melanin production. Therefore, comprehensive sun protection is crucial for managing melasma.

Hormonal Influences

Hormones play a crucial role in the development of melasma, especially during pregnancy. During the third trimester of pregnancy, levels of oestrogen, progesterone, and melanocyte-stimulating hormone increase, which can trigger melasma. This condition is often referred to as the “mask of pregnancy.” Women who are not pregnant but have melasma may show elevated levels of oestrogen receptors in their skin lesions. Additionally, women who take birth control pills or undergo hormone treatments, such as those for prostate cancer, may develop melasma due to the hormones in these medications. Postmenopausal women who are given progesterone might develop melasma, whereas those who take only oestrogen usually do not. This implicates progesterone as a primary factor in melasma development.

Thyroid Disease

There is a notable increase in thyroid disease among people with melasma, suggesting a connection between the two conditions. Additionally, there is an association between melasma and the presence of melanocytic nevi (moles) and lentiginous nevi (age spots), indicating a relationship between melasma and skin pigmentation issues.

Who Gets Melasma? (Epidemiology)

Melasma can affect individuals of any race, but it is more common in people with darker skin types, particularly those with light brown skin. Women are nine times more likely to develop melasma than men. The condition is rare before puberty and is most common during the reproductive years, affecting 15% to 50% of pregnant women. The prevalence of melasma varies widely, from 1.5% to 33%, depending on the population studied.

How Melasma Develops (Pathophysiology)

The most critical factor in the development of melasma is exposure to sunlight. UV radiation induces the production of alpha-melanocyte-stimulating hormone, corticotropin, interleukin 1, and endothelin 1 in the skin, leading to increased melanin production. Prolonged exposure to UV radiation causes dermal inflammation and activation of fibroblasts, which further increase melanogenesis (melanin production).

Changes in the Skin (Histopathology)

In melasma, melanin can increase in both the dermis (the deeper layer of the skin) and the epidermis (the outer layer of the skin). In the epidermis, melanin is found in keratinocytes, the cells in the basal and suprabasal layers. In the dermis, melanin is located in the superficial and mid-dermis within macrophages, which are cells that congregate around small, dilated blood vessels. Inflammation in melasma-affected skin is minimal or absent.

Symptoms and Physical Examination

Melasma presents as symmetrically distributed hyperpigmented macules (flat, discoloured areas) on sun-exposed parts of the face, such as the cheeks, upper lip, chin, and forehead. These patches can worsen with excessive sun exposure.

Diagnosing Melasma (Evaluation)

Laboratory tests are generally not necessary to diagnose melasma. However, some studies suggest that there may be mild abnormalities in thyroid function associated with melasma, particularly in cases related to pregnancy or oral contraceptive use. In such instances, thyroid function tests might be considered. A Wood lamp examination can help localize the pigment to the dermis or epidermis, aiding in the diagnosis and treatment planning.

Treatment and Management

The best treatment for melasma involves a combination of topical creams and avoiding sun and oestrogen exposure. Here are some of the treatment options:

Topical Treatments

• • Hydroquinone Cream: This is the most effective treatment and works by lightening the dark patches on the skin.

• • Triple Combination Cream: This cream contains hydroquinone (4%), tretinoin (0.05%), and fluocinolone acetonide (0.01%) and is very effective in treating melasma. If this combination is unavailable or if the patient is sensitive to it, dual or single-agent treatments can be used.

Sun Protection

Using high-SPF sunscreens (50 or higher) can help prevent melasma from developing or worsening. It’s crucial to apply sunscreen daily and reapply it throughout the day, especially when spending time outdoors.

Chemical Peels

Chemical peels use glycolic or salicylic acids to increase the turnover of hyperpigmented keratinocytes (skin cells). These peels can help lighten the dark patches. Lightening agents are often used in conjunction with superficial peels for better results. However, close monitoring is necessary to avoid changes in pigmentation of the surrounding skin.

Lasers

Lasers can be used to treat melasma, but their efficacy can be unpredictable, and they often result in undesired cosmetic outcomes. Therefore, lasers are considered a second-line treatment and are used only if topical treatments have failed. Chemical peels and lasers should be performed by experienced professionals to minimize the risk of adverse effects such as skin damage and scarring.

Other Conditions to Consider (Differential Diagnosis)

When diagnosing melasma, it is essential to consider other conditions that can cause similar symptoms. These include:

• • Actinic Lichen Planus

• • Acanthosis Nigricans

• • Discoid Lupus Erythematosus

• • Drug-Induced Photosensitivity

• • Exogenous Ochronosis

• • Frictional Melanosis

• • Mastocytosis

• • Nevi of Ito and Ota

• • Pigmented Contact Dermatitis

• • Poikiloderma of Civatte

• • Post inflammatory Hyperpigmentation

Outlook and Prognosis

Melasma does not cause serious health problems and does not increase the risk of skin cancer. In fact, patients with melasma are considered to have a lower risk of melanoma (a type of skin cancer). The pigment in the deeper layers of the skin (dermal pigment) takes longer to fade than that in the upper layers (epidermal pigment). Strict sun avoidance is essential to prevent melasma from recurring.

Important Tips for Patients

Patients with melasma should take several precautions to manage their condition effectively:

• • Avoid Cosmetics on Sensitive Skin: Using cosmetics on sensitive skin can worsen melasma.

• • Do Not Rub Creams Vigorously: Rubbing creams too hard on dark patches can make the condition worse.

• • Education on Sun Avoidance: It’s crucial to avoid sun exposure as much as possible. Wearing a wide-brimmed hat and using broad-spectrum sunscreen with a high SPF can help protect the skin from UV radiation.

• • Use of Bleaching Creams: Bleaching creams should be applied only to the dark areas of the skin. It can take several months to see improvement, so patients should be patient and consistent with their treatment.

• • Avoid Trigger Medications: If possible, patients should avoid medications that can trigger melasma, such as certain birth control pills and hormone therapies.

Role of Healthcare Workers

Healthcare workers, including nurse practitioners, dermatologists, and primary care providers, play a crucial role in managing melasma. They should educate patients on the importance of avoiding sun exposure and discontinuing trigger medications. They should also guide patients on the use of topical treatments and the risks associated with procedures like chemical peels and lasers.

Enhancing Healthcare Team Outcomes

Melasma is a benign skin disorder with no morbidity. The primary reason patients seek treatment is for aesthetic concerns. Fortunately, melasma often resolves on its own in most cases. Therefore, healthcare workers should focus on educating patients about sun avoidance and the potential triggers of melasma. There are many treatments available, but no single treatment is superior to the others. In fact, some treatments, like lasers, may worsen the condition.

Conclusion

Melasma is a common and challenging skin condition that primarily affects women and individuals with darker skin types. It is characterized by brown to grey-brown patches on the face and is influenced by factors such as genetics, hormonal changes, and UV exposure. While melasma does not pose a health risk, it can significantly impact a person’s appearance and self-esteem. Effective management requires a combination of sun protection, topical treatments, and patient education. With proper care and consistent treatment, many patients can achieve significant improvement in their skin’s appearance and quality of life.