Melasma (Chloasma) (Masque de grossesse): Epidemiologie et Facteurs de Risque

Ethymology

• melasma comes from the Greek word “melas” which means black
• chloasma comes from the Greek word “chloe” which means green grass

Epidemiology

• Geographical Factors

1. affected 5 million people in the USA in 1955
2. affects 8.8% of Latino (Hispanic) females
3. affects 40% of females in South-East Asia
4. affects 80% of males in South-East Asia !

• Gender Factors

1. women are affected 9 times more often than men

Clinical characteristics

• dark skin Types (III and above) are affected more than fair skin-types
• distribution usually symetrical
• the color can be light brown, dark brown, grey brown
• localized on the face sometimes on the neck

Risk factors

• skin type more of than Fitzpatrick type III
• genetic background

1. 48% of affected patients report a family history
2. 54.7% of affected patients in an Iranian study report a family history with a first degree relative affected

• Hormonal hyperestrogenic states

1. oral contraceptive pill
2. pregnancy (thus the term pregnancy mask)
3. estrogen receptors have been found in melanocytes of melasma lesions

• Sun exposure

1. melasma is worse with sun exposure
2. melasma fades after sun avoidance
3. melasma repigments more than the inital lesion if one is re-exposed to the sun
4. UV radiation promotes the following: Interleukin 1 (Il-1), Endothelin 1, Alpha MSH, ACTH…more than 1500 genes are involved

more blood vessels in melasma lesions compared to perilesional skin

When does it appear ? (study by Ortonne JP et al.)

• mean age of onset: 34 years old
• a family history is reported by 48% of affected patients (of which 97% are first degree relatives)
• The overwhelming majority has a skin type of more more than III
• 42% of new melasma cases were during pregnancy
• 25% of new melasma cases were under oral contraceptive treatment

Contributors:

Dr Christophe HSU – dermatologist. Geneva, Switzerland

Source of information:

Katsambas A. Melasma: Pathogenesis and Treatment. 70e Réunion annuelle de l’AAD (American Academy of Dermatology) – San Diego, California, United States of America (USA)

SY 20. Hyperpigmentation. Katsambas A. Melasma Pathogenesis and Treatment. What’s New ? 2012 (06) – 9th Spring Symposium of the EADV (European Academy of Dermatology and Venerology) – Verona, Italy (Italia)