Melasma (Chloasma) (Pregnancy Mask) Diagnostic elements, epidemiology and importance of sunprotection

Skin color is determined by:

• The type of melanin
• The amount of melanin in melanocytes
• The distribution pattern in surrounding keratinocytes

The term melasma comes from Greek melas: black

Etiology: The exact cause is unknown but some factors play a role

• Ultraviolet light (UV)
• genetic factors
• thyroid disturbances
• cosmetics
• hormonal factors (in females)

Epidemiology

• The incidence is unknown
• It affects around 6 million people in the USA

The Prevalence is highest in

• hispanics
• East Asians
• Individuals with Phototypes Fitzpatrick IV to VI
• Individuals living in areas of intense Ultraviolet (UV) irradiation

Females are more affected than males:

• female-male ratio 9 to 1
• also men: 10% Caucasian, 26% Indians….

Types

• based on the depth of the pigment in the skin

1. epidermal
2. dermal
3. mixed
4. indeterminate

• based on distribution

1. centrofacial
2. malar
3. mandibular

Concerning the treatment of Melasma (Chloasma) (Pregnancy Mask): what one needs to know is that sun exposure, whether only once or repeated worsens melasma (chloasma)(pregnancy mask):

• A single exposure to Ultraviolet light (UV) increases the size of melanocytes and tyrosinase activity.
• Chronic exposure increases the number of melanosomes (organelles in melanocytes which contain melanin) and their transfer to the surrounding keratinocytes

Contributors:

Dr Christophe HSU – dermatologist. Geneva, Switzerland

Source of information: Handog E. Brown Spots: Melasma Updates.2012 (02) – 20th Regional Conference of Dermatology (RCD) – Manila, Phillipines

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