At a Glance - Necrobiosis lipoidica versus granuloma annulare

Contributed by Dr Jean Watkins, a retired GP in Hampshire.

Necrobiosis lipoidica
Necrobiosis lipoidica

Necrobiosis Lipoidica

Aetiology

  • A rare skin condition in which there is collagen degeneration with granulomatous response, thickened blood vessels and deposition of fat.
  • Cause unknown but more often occurs in, or precedes, the development of diabetes.
  • More common in women.
  • May occur at any age but commonly around 30 years.

Presentation

  • Initial small, well-circumscribed papules or nodules spread to form reddish/brown plaques that become waxy and atrophic.
  • Telangiectases on surface.
  • Usually occur on pretibial area. Often bilateral.
  • Lesions sometimes ulcerate and/or may become infected.

Investigations

  • Check urine for glucose in patients without diabetes and perform further checks in case it develops later.

Management

  • Protect legs from trauma, with support stockings to reduce risk of ulceration.
  • Tends to run chronic course; poor response to treatment.
  • Early lesions may be helped by topical or intralesional steroids to active borders.
  • Combined aspirin and dipyridamole.
  • Pentoxifylline
  • Ciclosporin
  • Photochemotherapy - psoralen with UVA (PUVA).

Granuloma Annulare (GA)


Aetiology

  • Common skin condition; no cause has been found but possible genetic link.
  • Sometimes linked with type 1 diabetes. Rarely linked with type 2 diabetes.
  • May occur at any age but most commonly occurs in children and young adults.

Presentation

  • May occur anywhere on skin. Usually no symptoms.
  • Localised GA: tends to occur over joints such as knuckles, back of hands, elbows or foot. Groups of small papules, erythematous or flesh-coloured, often annular pattern.
  • Generalised GA: widespread small flesh-coloured erythematous or mauve papules coalesce, forming plaques that gradually enlarge. More likely to be associated with diabetes.
  • Perforating GA: Multiple small pink or reddish papules at any site. May become pustular and exude clear or creamy fluid. Larger ulcerated plaques can develop.

Investigation

  • Usually a clinical diagnosis, but this can be confirmed by biopsy if necessary.

Management

  • May resolve spontaneously within a few months, especially localised GA. Response to treatment unreliable.
  • Some may persist for years. Generalised GA tends to be more persistent.
  • If necessary can be helped by potent topical or intralesional steroid, imiquimod, tacrolimus or pimecrolimus.
  • Cryotherapy may improve small plaques.
  • Isotretinoin or PUVA.

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