Skin problems on the arms

Links to pages about skin conditions that favour the arms.

• Erythema
• Red papules/pustules
• Erosions, crusting
• Dry scaly and itchy
• Dry scaly but not very itchy
• Skin coloured papules
• Pigmentary changes

Arms: erythema without surface change

Erythema is less pronounced in dark skin.

Sunburn

• Sun-exposed site
• Painful
• Consider phototoxic drugs

Urticaria

• 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

Impetigo

• Irregular enlarging plaque
• Honey-coloured crusts
• Culture: Staphylococcus aureus +/- Streptococcus pyogenes

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

• Coin-shaped plaques
• Consider autoeczematisation from other site

Arms: dry and scaly with minimal itch

Keratosis pilaris

• Follicular papules
• Extensor upper arms

Psoriasis

• 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

Vitiligo

• Most often volar wrists
• White, smooth surface

See also pigmentary disorders