Melasma / Chloasma

Definition

• Melasma (also referred to as chloasma) is an acquired hyperpigmentation disorder that typically presents with irregular brownish patches on the upper lip, cheeks, and forehead. It occurs due to excess melanin deposition in the skin and is more common in women.

Aetiology & Triggers

• UV Exposure: Major modifiable risk factor (sun exposure stimulates melanocytes).

• Pregnancy: Hormonal changes can stimulate melanocytes (the so-called “mask of pregnancy”).

• Family History: Genetic predisposition.

• Hormonal Therapy: Oral contraceptives (OCPs) and HRT can exacerbate melasma.

• Hypothyroidism: Occasionally linked to melasma.

• Cosmetic Products: Perfumes or scented soaps may irritate and worsen pigmentation.

Clinical Features

• Melanin Deposition in basal & suprabasal keratinocytes

• Hyperpigmented, dendritic melanocytes present

• Dermal Melanophages (melanin-laden macrophages) can lead to deeper, more refractory pigmentation

• Solar Elastosis and elastic fibre fragmentation in chronic sun-exposed areas

• Often increased skin vascularity in affected regions

Differential Diagnosis

• Post-Inflammatory Hyperpigmentation (PIH)

• Solar Lentigo, Freckles (ephelides), other lentigines

• Acquired Dermal Macular Hyperpigmentation (e.g. Riehl melanosis)

• Drug-Induced Hyperpigmentation (e.g. minocycline)

• Naevus of Ota, Naevus of Hori (congenital or acquired dermal melanocytosis)

Management

Sun Protection

• Physical UV Blockers (e.g. zinc oxide, titanium dioxide) essential for preventing exacerbation.

• Use broad-brimmed hats, sunglasses, and avoid midday sun.

First-Line Therapy

• Hydroquinone 2% cream once or twice daily for 2–4 months.

  • Consider a test area initially (risk of irritant or allergic reactions).

  • Limit continuous use to 4–6 months to reduce side effects (e.g. exogenous ochronosis).

If No Response

• Combination therapy: Tretinoin + Hydroquinone (± topical steroid).

  • Start with a low dose tretinoin to minimise irritation.

  • Build up as tolerated.

Second-Line

• Topical Retinoid alone (e.g. tretinoin) if hydroquinone not tolerated or contraindicated.

  • Avoid retinoids in pregnancy or breastfeeding.

Laser & Chemical Peels

• Not routinely recommended: risk of post-inflammatory hyperpigmentation or paradoxical darkening.

Notes

• Emphasise long-term sun avoidance and consistent sun protection to maintain improvement.

• Check for any underlying hormonal issues if persistent or refractory.

• In pregnancy, manage conservatively as many cases fade postpartum.