Differential diagnoses - Pigment formation

Dr Nigel Stollery explains the differences between four common skin pigment conditions.

Postinflammatory hyperpigmentation

Presentation

  • Occurs anywhere on the body.
  • More commonly seen in darker-skinned patients.
  • Develops after inflammatory skin conditions such as eczema or acne.

Management

  • Treatment usually not required.
  • Treating the underlying condition will reduce further pigment formation.
  • Topical retinoids can be helpful.
  • Avoiding UV exposure will reduce the degree of pigmentation.
  • Sunblocks should be used, even in darker-skinned patients.

Freckles

Presentation

  • Well-demarcated 1-5mm orange-brown macules.
  • Occur on sun-exposed sites, such as face, hands and forearms.
  • Usually much reduced in the winter months.
  • More common in those with type I skin (red hair, pale skin).
  • Histologically, normal numbers of melanocytes, but increased pigment.

Management

  • No treatment necessary.
  • Sunblock use can help to reduce pigment.

Chloasma

Presentation

  • Symmetrical distribution, occurring mainly in women.
  • Affects forehead, cheeks and upper lip.
  • Occurs most commonly in association with pregnancy and use of the combined oral contraceptive pill (COC).

Management

  • Usually fades after pregnancy or with cessation of the COC.
  • Pigment more pronounced with UV light exposure.
  • Sunblock can be helpful in lightening pigment.
  • 4% hydroquinone alone or in combination with a retinoid can be helpful.

Poikiloderma of Civatte

Presentation

  • Occurs in middle-aged and older patients.
  • Pigment presents at the sides of the neck, with sparing under the chin.
  • Associated with telangiectasia and atrophy.
  • Mottled red-brown colour.

Management

  • No reliable treatment available.
  • Exacerbated by UV light, so sunblock can be helpful.
  • Possibly associated with photosensitisers, such as perfumes.
  • Lasers can be helpful in reducing pigment.

Dr Stollery is a GP in Kibworth, Leicestershire, and clinical assistant in dermatology at Leicester Royal Infirmary.

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