Skin problems on the arms

Author: Hon Assoc Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand, September 2015.

Links to pages about skin conditions that favour the arms.

Arms: erythema without surface change

Erythema is less pronounced in dark skin.


  • Sun-exposed site
  • Painful
  • Consider phototoxic drugs


  • Weals can arise on any site
  • Spontaneous and inducible types

Arms: red papules/pustules

Acne vulgaris

  • Upper trunk
  • Open and closed comedones
  • Nodules + cysts if severe

Insect bites

  • Crops of grouped itchy papules
  • Central punctum
  • May blister

Lichen planus

  • Inside wrists
  • Firm, violaceous papules + white streaks
  • Favours areas of earlier injury
  • Also examine mouth, lower back, lower legs

Arms: erosions/crusting

Herpes zoster

  • Dermatomal
  • Painful
  • Erythema may precede vesicles
  • Culture/PCR: Herpes varicella zoster


Scabies rash

  • Burrows between fingers, wrists
  • Nodules in axillae, groin
  • Intense itch, especially at night
  • Dermatoscopy of burrow reveals mite

Arms: dry/scaly and very itchy

May also blister, swell.

Allergic contact dermatitis

  • Acute flares on any site
  • Asymmetrical, odd-shaped patches/plaques
  • Patch tests positive

Atopic dermatitis

  • Patchy or diffuse
  • Acute flares are erythematous
  • Chronic eczema is lichenified

Nummular dermatitis

Arms: dry and scaly with minimal itch

Keratosis pilaris

  • Follicular papules
  • Extensor upper arms


  • Roughly symmetrical distribution
  • Extensor elbows
  • Well-circumscribed erythematous scaly plaques
  • Variable itch

Arms: multiple skin coloured papules

Granuloma annulare

  • Extensor elbows, dorsum of hands and fingers
  • Arranged in rings

Pigmentary changes

Pigmentation is more pronounced in dark skin.

Postinflammatory pigmentation

  • Preceding eczema, psoriasis, acne etc
  • Distribution depends on cause


  • Most often volar wrists
  • White, smooth surface

See also pigmentary disorders

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