Melasma (Chloasma) (Pregnancy Mask): Epidemiology and Risk Factors
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
- affected 5 million people in the USA in 1955
- affects 8.8% of Latino (Hispanic) females
- affects 40% of females in South-East Asia
- affects 80% of males in South-East Asia !
- Gender Factors
- 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
- 48% of affected patients report a family history
- 54.7% of affected patients in an Iranian study report a family history with a first degree relative affected
- Hormonal hyperestrogenic states
- oral contraceptive pill
- pregnancy (thus the term pregnancy mask)
- estrogen receptors have been found in melanocytes of melasma lesions
- Sun exposure
- melasma is worse with sun exposure
- melasma fades after sun avoidance
- melasma repigments more than the inital lesion if one is re-exposed to the sun
- 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)
