From the Guidelines
Melasma pathogenesis involves a complex interplay of ultraviolet radiation, hormonal influences, genetic predisposition, inflammation, vascular factors, and oxidative stress, making it a challenging condition to treat and prone to recurrence. The primary trigger for melasma is ultraviolet radiation, which stimulates melanocytes to increase melanin production 1. Hormonal influences, particularly estrogen and progesterone, also play a significant role in melasma development, explaining its higher prevalence in women, especially during pregnancy or with oral contraceptive use. Key factors contributing to melasma pathogenesis include:
- Ultraviolet radiation as the primary trigger
- Hormonal influences, such as estrogen and progesterone
- Genetic predisposition, with higher frequency in individuals with darker skin types (Fitzpatrick III-VI) and those with a family history
- Inflammation, through the release of inflammatory mediators that stimulate melanogenesis
- Vascular factors, with increased vascularity observed in melasma lesions
- Oxidative stress, damaging cell membranes and DNA, leading to melanocyte dysfunction and hyperpigmentation Effective management of melasma requires a comprehensive approach, including an effective home care routine, adequate sun protection, and regular follow-ups, as it should be managed as a chronic condition 1.
From the Research
Melasma Pathogenesis
- 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, genetic factors, hormonal activity, stress, and some cosmetic products and drugs containing phototoxic agents 2, 3.
- The pathogenesis of melasma is highly complex, involving multiple pathologies outside of skin pigment cells, including photoaging, excessive melanogenesis, an increased number of mast cells, increased vascularization, and basement membrane damage 3.
Factors Contributing to Melasma
- Sun exposure is a major contributing factor to the development of melasma, with ultraviolet radiation stimulating the production of melanin in the skin 2, 3.
- Hormonal activity, particularly in females, plays a significant role in the development of melasma, with the onset of melasma often occurring during puberty or later in life 2.
- Genetic factors also contribute to the development of melasma, with a higher prevalence of the condition in individuals with darker skin types (Fitzpatrick skin types IV to VI) 2, 4.
Molecular Mechanisms
- Melasma is characterized by an overproduction of melanin in areas exposed to ultraviolet radiation, with skin lesions related to melasma and their surrounding skin having nearly 300 genes differentially expressed from healthy skin 3.
- The condition involves increased epidermal and/or dermal pigmentation, enlarged melanocytes, increased melanosomes, solar elastosis, dermal blood vessels, and, occasionally, perivascular lymphohistiocytic infiltrates 4.