Melasma

 Melasma

Common acquired symmetric brown hyperpigmentation involving the face/neck. Can be faint or dark and can have devastating psychosocial impact.

Etiology

Caused by genetic factors, UV Radiation, Pregnancy, Oral Contraceptives, Estrogen-Progesterone therapies, thyroid dysfunction, cosmetics, and phototoxic and antiseizure drugs.  May not resolve after delivery of baby or after withdrawal of oral contraceptives

Clinical Features

Three clinical patterns:

1)       Centrofacial

2)       Malar

3)       Mandibular

Four types based on Wood’s light exam

1)       Epidermal type: increased melanin in the basal, suprabasal, & stratum corneum layers. Pigmentation is intensified with Wood’s light exam. Responds to depigmenting agents

2)       Dermal type: No enhancement of pigmentation with Wood’s light. Melanophages are found in superficial dermis and in deep dermis. Resists the action of bleaching agents

3)       Mixed-type Epidermal and Dermal Pigment Type: no or slight enhancement with Wood’s light

4)       Wood’s light inapparent: seen in dark individuals

The forehead, malar eminences, upper lip and chin are most commonly affected.  Occurs during 2nd or 3rd trimester of pregnancy, gradually fades after delivery and darkens with subsequent pregnancies

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