What rheumatological conditions can cause rashes or skin lesions in adults?

Rheumatological Conditions Causing Rashes and Skin Lesions

Multiple rheumatological conditions present with characteristic skin manifestations, with systemic lupus erythematosus, dermatomyositis, and psoriatic arthritis being the most common culprits that require immediate recognition for early diagnosis and treatment. 1, 2

Primary Rheumatological Conditions with Skin Involvement

Systemic Lupus Erythematosus (SLE)

SLE presents with three distinct cutaneous patterns that are critical for diagnosis and risk stratification 1, 2:

• Acute Cutaneous Lupus (ACLE): Classic "butterfly" or malar rash across the cheeks and nasal bridge, highly photosensitive and often indicates active systemic disease 1, 3
• Subacute Cutaneous Lupus (SCLE): Annular or psoriasiform photosensitive lesions, strongly associated with anti-Ro/SSA antibodies (present in 70-90% of cases), and may be drug-induced 2, 4, 3
• Chronic Cutaneous Lupus (CCLE): Discoid lesions with scarring, atrophy, and permanent pigmentary changes, which can occur with or without systemic involvement 1, 4

Non-specific cutaneous manifestations include diffuse exanthema, cutaneous vasculitis presenting as palpable purpura or digital necrosis, alopecia (scarring in discoid lupus, non-scarring in active SLE), and oral ulcers 1, 3. These non-specific lesions often correlate with disease flares and systemic activity 3.

Dermatomyositis (DM)

Dermatomyositis has pathognomonic skin findings that frequently precede muscle weakness by weeks to months, making dermatologic recognition crucial for early diagnosis 5, 3:

• Gottron's papules: Violaceous papules over the dorsal metacarpophalangeal and interphalangeal joints 5, 3
• Gottron's sign: Erythematous macules over extensor surfaces of elbows, knees, and ankles 5, 3
• Heliotrope rash: Violaceous periorbital edema with or without erythema 5, 3
• Shawl sign: Erythema over the shoulders, upper back, and V-neck area 5
• Mechanic's hands: Hyperkeratotic, fissured skin on the lateral and palmar aspects of fingers 5
• Nailfold capillary abnormalities: Dilated capillary loops and periungual telangiectasias visible on dermoscopy 3

Critical pitfall: Specific autoantibody patterns predict phenotypes—anti-MDA-5 antibodies indicate higher risk for rapidly progressive interstitial lung disease (potentially fatal), while anti-TIF1-γ antibodies are associated with increased malignancy risk 3. Cutaneous vasculitis and ulcerations are more common in juvenile dermatomyositis 5.

Psoriatic Arthritis

Psoriatic arthritis typically presents with psoriatic skin lesions before or concurrent with joint involvement 3, 6:

• Plaque psoriasis: Well-demarcated erythematous plaques with silvery scale, commonly on extensor surfaces, scalp, and gluteal cleft 3
• Nail changes: Pitting, onycholysis, oil spots, and subungual hyperkeratosis occur in 80-90% of patients with psoriatic arthritis 3
• Pustular eruptions: Palmoplantar pustulosis may be associated with SAPHO syndrome (Synovitis, Acne, Pustulosis, Hyperostosis, Osteitis) 6

Rheumatoid Arthritis (RA)

While primarily a joint disease, RA has several cutaneous manifestations 7:

• Rheumatoid nodules: Firm subcutaneous nodules over pressure points (elbows, fingers, Achilles tendon), present in 20-30% of seropositive patients and indicate more severe disease 5, 7
• Rheumatoid vasculitis: Palpable purpura, digital infarcts, leg ulcers, or livedo reticularis in severe, long-standing disease with high rheumatoid factor titers 3, 7
• Neutrophilic dermatoses: Pyoderma gangrenosum and Sweet's syndrome can occur 7

Important caveat: Many RA therapies cause cutaneous adverse effects—anti-TNF agents commonly induce psoriasiform eruptions, granulomatous conditions, and paradoxically can trigger lupus-like syndromes 8, 7. Methotrexate causes photosensitivity, alopecia, and oral ulcers in 3-15% of patients 8.

Systemic Sclerosis (Scleroderma)

Scleroderma presents with progressive skin thickening and vascular abnormalities 3, 9:

• Skin thickening: Begins distally on fingers and progresses proximally, with loss of skin folds and bound-down appearance 3, 9
• Raynaud's phenomenon: Nearly universal, often the initial manifestation with triphasic color changes (white-blue-red) 3
• Digital ulcers and pitting scars: Result from severe vasculopathy 9
• Telangiectasias: Mat-like telangiectasias on face, hands, and mucous membranes 9
• Calcinosis cutis: Calcium deposits in subcutaneous tissue, particularly in limited cutaneous systemic sclerosis (CREST syndrome) 9

Sjögren's Syndrome

Cutaneous manifestations are less prominent but include 3:

• Xerosis: Dry skin from decreased sweat and sebaceous gland function 3
• Purpura: Palpable purpura from small vessel vasculitis, often on lower extremities 3
• Annular erythema: Erythema annulare centrifugum-like lesions 3

Less Common but Important Associations

Vasculitis Syndromes

Various vasculitides present with characteristic cutaneous findings 5, 3, 6:

• Small vessel vasculitis: Palpable purpura, typically on dependent areas (lower legs), seen in ANCA-associated vasculitis, IgA vasculitis (Henoch-Schönlein purpura), and cryoglobulinemic vasculitis 5, 6
• Medium vessel vasculitis: Livedo reticularis, nodules, and ulcers in polyarteritis nodosa 6
• Large vessel vasculitis: Scalp tenderness and necrosis in giant cell arteritis 5

Behçet's Disease

Behçet's disease presents with recurrent oral and genital ulcers, pathergy (pustule formation at needle stick sites), and erythema nodosum 3, 6.

Autoinflammatory Syndromes

Adult-onset Still's disease and hereditary autoinflammatory syndromes present with 6:

• Evanescent salmon-pink macular rash: Appears with fever spikes and resolves within hours 6
• Urticarial lesions: Non-pruritic, often accompanying systemic symptoms 6

Sarcoidosis

Sarcoidosis can present with skin manifestations including papules, nodules, plaques, and lupus pernio (violaceous indurated lesions on nose, cheeks, and ears) 5.

Diagnostic Approach Algorithm

When evaluating a patient with rash and suspected rheumatological disease 1, 2, 4:

1. Classify the morphology and distribution: Malar distribution suggests SLE; periorbital violaceous changes suggest dermatomyositis; extensor plaques suggest psoriasis; skin thickening on fingers suggests scleroderma 1, 2, 3

2. Perform skin biopsy: Mandatory for histological confirmation, looking for interface dermatitis (lupus), perivascular inflammation (vasculitis), or granulomas (sarcoidosis) 1, 2, 4

3. Order comprehensive autoantibody panel: ANA, anti-dsDNA, anti-Ro/SSA, anti-La/SSB, anti-RNP, anti-Sm, RF, anti-CCP, ANCA, and anti-phospholipid antibodies 1, 2

4. Measure complement levels: C3 and C4 are typically low in active SLE 1, 2

5. Assess for systemic involvement: CBC, ESR, CRP, creatinine, urinalysis with protein/creatinine ratio, and organ-specific testing based on clinical suspicion 1, 2

6. Use validated disease activity indices: CLASI for cutaneous lupus, SLEDAI or BILAG for systemic lupus 1, 2

Critical Management Principles

Photoprotection is mandatory for all photosensitive conditions (SLE, dermatomyositis, SCLE), requiring SPF 60+ sunscreen, sun avoidance between 10 AM-4 PM, and protective clothing 1, 4.

Smoking cessation is essential as smoking impairs response to antimalarial therapy in lupus 1.

First-line systemic therapy for cutaneous lupus not controlled with topical corticosteroids is hydroxychloroquine 200-400 mg daily, requiring baseline and annual ophthalmologic screening for retinal toxicity 1, 4.

Common pitfall to avoid: Do not rely solely on ANA positivity for diagnosis, as it can be positive in healthy individuals and other conditions; always correlate with clinical findings and specific autoantibodies 2. Additionally, autoantibodies may be absent in checkpoint inhibitor-induced rheumatic conditions despite classic clinical presentations 5.