melasma
MELASMA
Melasma is an acquired hypermelanosis skin disorder that commonly affects women than men. It is characterized by irregular light to dark brown macules occurring in the sun-exposed areas of the face, neck and arms.
It occurs most commonly with pregnancy and with the use of contraceptive pills.
Other factors implicated in the etiopathogenesis are photosensitizing medications, mild ovarian or thyroid dysfunction and certain cosmetics.
Solar and ultraviolet exposure is the most common important factor in its development.

Diagnosis

Diagnosis is based on clinical characteristics

Assessment

Woods Lamp Exam

  • Used to visually localize the excessive melanin to the epidermis, dermis, or both

Classification

  • Epidermal
    • Light brown, with enhancement of pigmentation under Wood’s light
    • Melanin increase in basal, suprabasal & stratum corneum layers with highly dendritic & pigmented melanocytes
    • Epidermal pigment is more amenable to treatment than dermal pigment
  • Dermal
    • Ashen or bluish-gray, no enhancement of pigmentation under Wood’s light
    • Perivascular melanophages on the superficial & deep dermis with less hyperpigmentation in the epidermal layer
  • Mixed
    • Dark brown, enhancement is seen in some areas only
    • Melanin deposition found in epidermis & dermis
  • Indeterminate
    • Inapparent under Wood’s light
    • Melanin deposition found in dermis

Physical Examination

  • Patient presents with well-demarcated tan to brown macular hyperpigmentation
  • Based on clinical pattern may be classified to:
    • Centrofacial is the most common type with macules & patches on the cheek, forehead, upper lip, nose & chin
    • Malar appears on cheeks & nose
    • Mandibular lesions are over the ramus of the mandible
  • Pigment may also have a bluish appearance
  • Severity may be measured using the Melasma Area & Severity Index (MASI), which relies on 4 areas involved: forehead, right malar region, left malar region, & chin
    • Grades the area involved & degree of pigmentation
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