Melasma

Introduction | Aetiology and Risk Factors | Clinical Presentation | Diagnosis | Management and Treatment | Prevention | When to Refer | References

Introduction

Melasma, also known as chloasma, is a common acquired skin condition characterised by symmetrical, hyperpigmented macules and patches. It predominantly affects sun-exposed areas of the skin, particularly the face. Melasma is more prevalent in women, especially during pregnancy or in those using oral contraceptives, and is often associated with hormonal changes. While the condition is benign, it can cause significant cosmetic concern due to its appearance.

Aetiology and Risk Factors

The exact cause of melasma is not fully understood, but several factors are known to contribute to its development:

• Hormonal Factors: Hormonal changes, such as those during pregnancy (often referred to as the "mask of pregnancy") or with the use of oral contraceptives and hormone replacement therapy, are strongly associated with melasma.
• Ultraviolet (UV) Radiation: Sun exposure is a significant risk factor, as UV radiation stimulates melanocytes to produce excess melanin, exacerbating melasma.
• Genetic Predisposition: A family history of melasma increases the likelihood of developing the condition, suggesting a genetic component.
• Skin Type: Melasma is more common in individuals with darker skin types (Fitzpatrick skin types III-V), who have more active melanocytes.
• Cosmetic Products: Certain cosmetics or skin care products, particularly those causing irritation, can trigger or worsen melasma.
• Medications: Some medications, such as anti-epileptic drugs, have been linked to melasma.

Clinical Presentation

Melasma typically presents with the following features:

• Hyperpigmented Macules and Patches: The hallmark of melasma is brown to grey-brown patches that are symmetrically distributed on the face. These patches are usually irregular in shape and vary in size.
• Common Sites: The most commonly affected areas include the cheeks, forehead, upper lip, nose, and chin. The neck and forearms may also be involved in some cases.
• Asymptomatic: Melasma does not cause itching or pain, but the cosmetic appearance can lead to significant psychological distress.
• Worsening with Sun Exposure: Melasma often darkens and becomes more noticeable during the summer months due to increased UV exposure.

Diagnosis

The diagnosis of melasma is primarily clinical, based on the characteristic appearance of the lesions and patient history:

• History: Assess the onset and progression of hyperpigmentation, any triggering factors such as pregnancy, oral contraceptive use, or sun exposure, and any family history of similar conditions.
• Physical Examination: Examine the face and other commonly affected areas for symmetrical, hyperpigmented patches. Wood’s lamp examination can help differentiate between epidermal (more superficial) and dermal (deeper) melasma by enhancing the contrast of pigmentation.
• Differential Diagnosis: Consider other causes of hyperpigmentation, such as post-inflammatory hyperpigmentation, lichen planus pigmentosus, and drug-induced hyperpigmentation. The symmetrical distribution and association with hormonal factors can help distinguish melasma from these conditions.
• Skin Biopsy: Rarely required, but a biopsy can confirm the diagnosis if there is uncertainty. Histopathology typically shows increased melanin in the basal and suprabasal layers of the epidermis.

Management and Treatment

The management of melasma focuses on reducing pigmentation, preventing further darkening, and addressing the cosmetic impact:

1. Sun Protection

• Broad-Spectrum Sunscreen: Daily use of a broad-spectrum sunscreen with a high SPF (30 or above) is essential. Physical blockers containing zinc oxide or titanium dioxide are particularly effective. Sunscreen should be reapplied every 2 hours when outdoors.
• Protective Clothing: Encourage the use of wide-brimmed hats, sunglasses, and protective clothing to minimise UV exposure.
• Sun Avoidance: Advise patients to avoid sun exposure, particularly during peak UV hours (10 a.m. to 4 p.m.).

2. Topical Treatments

• Azelaic Acid: Azelaic acid 15-20% cream or gel has both anti-inflammatory and depigmenting properties.

3. Psychological Support

• Counselling: Melasma can cause significant distress due to its impact on appearance. Referral for psychological support or counselling may be beneficial for patients struggling with self-esteem or anxiety related to the condition.

Prevention

Prevention strategies for melasma primarily focus on minimising sun exposure and avoiding known triggers:

• Sun Protection: Consistent use of broad-spectrum sunscreen, protective clothing, and sun avoidance is essential to prevent melasma or its recurrence.
• Avoiding Hormonal Triggers: Discuss alternatives to hormonal contraceptives or hormone replacement therapy with patients at risk of melasma. Non-hormonal methods may be preferable.
• Skin Care: Advise the use of gentle, non-irritating skin care products to reduce the risk of exacerbating melasma.

When to Refer

Referral to a dermatologist may be necessary in the following situations:

• Refractory Melasma: If melasma does not respond to standard treatments, referral for advanced therapies such as laser treatment or chemical peels may be warranted.
• Diagnostic Uncertainty: If the diagnosis is unclear or if there is concern for other conditions, such as post-inflammatory hyperpigmentation or drug-induced hyperpigmentation, further evaluation by a specialist is advised.
• Psychological Distress: If the patient experiences significant psychological impact due to melasma, referral for psychological support may be beneficial.

References

1. British Association of Dermatologists (2024) Guidelines for the Management of Melasma. Available at: https://www.bad.org.uk (Accessed: 26 August 2024).
2. National Institute for Health and Care Excellence (2024) Melasma: Diagnosis and Management. Available at: https://www.nice.org.uk/guidance/ng103 (Accessed: 26 August 2024).
3. British National Formulary (2024) Topical and Systemic Treatments for Dermatological Conditions. Available at: https://bnf.nice.org.uk/ (Accessed: 26 August 2024).