Understanding Melasma: A Specific Form of Hyperpigmentation
Melasma manifests as brown pigment spots, ranging from light to dark, often symmetrical and with irregular borders. These marks primarily affect the face, an area constantly exposed to sunlight. This condition is not simply a variation in color but a benign acquired hyperpigmentation. Types of melasma according to location: central facial (forehead, nose, cheeks, chin, upper lip), mandibular (jaw), and malar (cheeks and nose).It can also affect the forearms, areas rich in sebaceous glands. Particular attention should be paid to individuals with darker skin tones (II to VI), although melasma also occurs in lighter skin tones.
- It is common in women of childbearing age, especially during or after pregnancy. This often misunderstood condition can have a significant psychological impact. The relationship with appearance can become complicated, affecting well-being and self-esteem.
- Triggering Factors and the Multifactorial Nature of Melasma
- Melasma is not caused by a single factor. It is a complex combination of elements that activate excessive melanin production. Several factors influence its appearance:
- Genetics:
A family or individual predisposition may exist.
Sun Exposure:
UV and visible light stimulate pigment synthesis.
- Hormonal Factors: Estrogens during pregnancy, oral contraceptives, hormone replacement therapy, thyroid disorders.
- Prolonged exposure to heat and various forms of skin irritation (thermal, chemical, mechanical).
- A thorough medical history is essential to identify these factors, which vary from person to person. For example, a laser burn or the regular use of irritating cosmetic products can precipitate or worsen symptoms. Link between melasma and hyperpigmentation: key differences
- Hyperpigmentation refers to an abnormal increase in the skin’s melanin pigment, visible in several forms such as freckles, sunspots, or melasma. Melasma is a specific category of hyperpigmentation characterized by:
More diffuse and symmetrical patches on the face.
A more pronounced hormonal or environmental cause.
A more complex pathophysiological mechanism involving cellular interactions beyond just melanocytes. Unlike other forms of hyperpigmentation, melasma combines an inflammatory reaction with strong angiogenesis, causing visible pigment deposition in both the epidermis and dermis.
- This specific phenotype explains why treatment must be targeted and multifactorial.
- Biological Mechanisms of Melasma: A Profound Cellular Imbalance
In melasma, several skin cells are activated in concert:
Melanocytes:
hyperactivity leading to an overproduction of melanin.
Keratinocytes and fibroblasts:
- participate in pigment transmission and melanocyte stimulation. Mast cells and inflammatory cells:
- trigger a chronic inflammatory response. Endothelial cells:
- promote neovascularization, leading to altered skin structure. UV radiation amplifies this cascade, primarily via the cAMP pathway activated by MC1R receptors. Simultaneously, estrogens also modulate this pathway, which explains the frequency of melasma during hormonal changes, such as pregnancy or the use of contraceptives.
- Oxidative stress exacerbates this imbalance, fueling inflammatory and pigmentary mechanisms.
Anti-melasma treatments: acting on multiple levels
An effective therapeutic approach rests on several pillars:
Rigorous sun protection:
Use a sunscreen that combines protection against UVA, UVB, and visible light, reapplying it every two hours.
- Depigmenting agents:
- targeting melanin synthesis or transfer, such as hydroquinone, tretinoin, and mild corticosteroids. Oral treatments:
- such as tranexamic acid at a dosage of 250 mg morning and evening for a three-month course, acting on both melanogenesis and angiogenesis. Specific treatments:
- a four-phase protocol including gentle peels, topical treatments, and soothing care to prevent irritation. Renowned brands such as
La Roche-Posay, AvĂšne, SVR, Bioderma, Nuxe, Vichy, Caudalie, Lierac, Embryolisse and Erborian offer routines adapted for sensitive skin prone to these pigmentation disorders. Their expertise in formulations enriched with antioxidants, soothing agents, and brightening ingredients is invaluable.
For lasting effectiveness, treatment must also address emotional well-being, as melasma often impacts quality of life.
