What is the aetiology of melasma?

From the Guidelines

Melasma is primarily caused by a combination of ultraviolet (UV) exposure, hormonal influences, and genetic predisposition. The condition is more prevalent in females and individuals with darker skin types, and can be esthetically displeasing to the patient 1.

Key Factors Contributing to Melasma

• Ultraviolet (UV) radiation exposure, which triggers melanogenesis and worsens existing melasma
• Hormonal influences, particularly estrogen and progesterone, which explain why melasma is more common in women, especially during pregnancy, while using hormonal contraceptives, or during hormone replacement therapy
• Genetic predisposition, as melasma is more prevalent in individuals with darker skin types (Fitzpatrick types III-VI) and those with a family history of the condition
• Inflammation, whether from external irritants or internal factors, which can stimulate melanocytes and worsen hyperpigmentation

Additional Considerations

Other contributing factors include heat exposure, certain medications (like phototoxic drugs), thyroid disorders, and cosmetic products that irritate the skin 1.

Clinical Implications

Understanding the aetiology of melasma is crucial for developing effective treatment strategies, which may include topical therapies such as hydroquinone, tretinoin, corticosteroids, and tranexamic acid, as well as procedural therapies like autologous platelet concentrates (APCs) 1.

From the Research

Melasma Aetiology

• Melasma is a common, acquired facial skin disorder, mostly involving sun-exposed areas like cheeks, forehead, and upper lip 2.
• The etiology of melasma is still unknown, although there are several triggering factors related to its onset, including:
  • Sun exposure 2, 3
  • Genetic factors in both sexes 2, 3
  • Hormonal activity, particularly in females 2, 3, 4
  • Stress 2
  • Certain cosmetic products and drugs containing phototoxic agents 2
• Melasma occurs in both sexes, although almost 90 percent of the affected are women, and is more common in darker skin types (Fitzpatrick skin types IV to VI) 2.
• The onset of melasma is typically at puberty or later, with the exception of darker skin types, who tend to develop this problem in the first decade of life 2.

Triggering Factors

• Hormonal alterations or therapies, such as pregnancy, hormonal therapies, and oral contraceptive pills, have been reported to trigger melasma 4.
• Sun exposure is a significant triggering factor, and the use of UVA and UVB blocking sunscreens is beneficial in preventing melasma 2, 3.
• Certain cosmetic products and drugs containing phototoxic agents can also cause outbreaks of melasma 2.

Genetic Predisposition

• Genetic factors play a role in the development of melasma, particularly in individuals with a family history of the condition 2, 3.
• Melasma is more common in certain ethnic groups, such as Hispanics/Latinos, Asians, and African-Americans, suggesting a possible genetic predisposition 2.