Systemic Lupus Erythematosus (SLE)

Cutaneous types

Discoid lupus erythematosus (DLE)

•    Chronic, scarring, photosensitive plaques

•    Favour head and neck, scalp (→ alopecia)

•    May occur alone or as part of systemic lupus

Acute cutaneous lupus

•    Malar (butterfly) rash: spares nasolabial folds

•    Photosensitivity: exacerbated by sunlight

•    Oral and nasal ulcers: typically painless

•    Non-scarring, transient

Subacute cutaneous lupus

•    Annular or psoriasiform plaques

•    Highly photosensitive

•    Strong association with anti-Ro/SSA antibodies

Dermatomyositis

Key cutaneous signs

•    Heliotrope rash: violaceous periorbital oedema

•    Gottron’s papules: flat-topped violaceous papules over knuckles

•    Gottron’s sign: erythematous rash over extensor surfaces (elbows, knees)

•    "Shawl sign" and "V-sign": photosensitive erythema on upper back and chest

•    Nailfold capillary changes: dilated capillary loops, drop-out

Associations

•    Strong link with underlying malignancy (especially in older patients): ovarian, lung, colorectal, pancreatic

•    Also interstitial lung disease

Systemic Sclerosis (Scleroderma)

Cutaneous features

•    Skin thickening (sclerodactyly): tight, shiny skin; flexion contractures

•    Mask-like facies: reduced expression, beaked nose

•    Calcinosis cutis: calcium deposits in skin (part of CREST)

•    Telangiectasia: especially face, hands

•    Raynaud’s phenomenon: often first presentation; digital ulcers possible

CREST syndrome

•    Calcinosis

•    Raynaud’s

•    Esophageal dysmotility

•    Sclerodactyly

•    Telangiectasia

•    Associated with anti-centromere antibodies

Rheumatoid Arthritis

Cutaneous features

•    Rheumatoid nodules

o    Firm, non-tender, often on pressure points (e.g., elbows)

o    Associated with severe seropositive disease

•    Vasculitis-related skin changes

o    Purpura

o    Livedo reticularis

o    Ulcers

•    Pyoderma gangrenosum

o    Painful, rapidly expanding ulcers with undermined violaceous edges

o    Often precipitated by minor trauma (pathergy)

o    Also associated with IBD

Extra Revision Pearls

•    Photosensitivity is a unifying clue for lupus and dermatomyositis

•    Anti-Ro/SSA: associated with subacute cutaneous lupus and neonatal lupus (risk of congenital heart block)

•    Heliotrope rash + proximal weakness: classic dermatomyositis clue

•    Raynaud’s + sclerodactyly: think systemic sclerosis or CREST

•    Pyoderma gangrenosum: also linked to ulcerative colitis, not specific to RA