Hyperpigmentation

• Types:

  • Group 1 - serious causes e.g. Addison's, haemochromatosis
  • Group 2 - post inflammatory e.g. acne, eczema
  • Group 3 - drug reactions
  • Group 4 - melasma and other causes of more diffuse facial hyperpigmentation
  • Group 5 - localised hyperpigmentation of the face
  • Group 6 - hyperpigmentation of the neck e.g. acanthosis nigricans
  • Group 7 - lesion hyperpigmentation e.g. actinic lichen planus
• The melanocytes (pigment cells) are located at the base of the epidermis and produce the protein melanin. Melanin is carried by keratinocytes to the skin surface. The melanocytes of dark-skinned people produce more melanin than those of people with light skin. More melanin is produced when the skin is injured, for example following exposure to ultraviolet radiation. The melanisation process in dark skin is protective against sun damage, but melanisation in white skin (for example after sunburn) is much less protective.
• Hormonal effects of oestrogen during pregnancy or due to medication can cause pigmentation of nipples, vulva and abdomen (linea nigra).
• A Wood lamp may be used to assess pigmentation during the examination of the skin, as pigmentary changes are often easier to identify while exposing the affected skin to long-wavelength ultraviolet rays(UVA).
• Generalised hyperpigmentation or hypermelanosis may rarely arise from excessive circulating melanocyte-stimulating hormone (MSH) when it often has a bronze hue. It occurs:

  • In 95% of patients with Addison disease when it is more prominent on pressure areas, in skin folds, on scars, and within the mouth
  • In 90% of patients with haemochromatosis, when it is more prominent on the genitals, in skin folds, and on sun-exposed sites
  • Rarely in metastatic melanoma: diffuse melanosis cutis
• The following agents can be used to lighten epidermal melanosis alone or, more effectively, in combination:

  • Hydroquinone
  • Topical retinoid
  • Topical corticosteroid
  • Glycolic acid and other fruit acids
  • Azelaic acid
  • L-ascorbic acid (vitamin C)
• Resurfacing using chemical peels, laser (especially picosecond laser), intense pulsed light (IPL) or dermabrasion may be effective but unfortunately risks further damage to the epidermis and formation of more pigment