Causes of Digital Ulcers
Primary Etiology: Systemic Sclerosis-Related Vasculopathy
Digital ulcers occur most commonly as a vascular complication of systemic sclerosis (SSc), affecting approximately 50% of SSc patients during their disease course, with a point prevalence of 10-15%. 1, 2
The pathophysiology centers on structural alterations in digital arteries combined with vasospasm, leading to tissue ischemia 1. This represents the dominant cause in clinical practice, particularly in patients with diffuse cutaneous SSc and anti-topoisomerase I (anti-Scl70) antibody positivity 3, 4, 5.
Autoimmune and Connective Tissue Disease Causes
Beyond systemic sclerosis, several autoimmune conditions cause digital ulcers through similar vasculopathic mechanisms:
- Systemic lupus erythematosus causes digital ulcers through vasculitis and thrombotic vasculopathy 6
- Rheumatoid arthritis can produce digital ulcers, though less frequently than SSc 6
- Mixed connective tissue disease shares overlapping features with SSc and similar ulcer risk 6
Vascular and Thrombotic Disorders
Arterial Occlusive Disease
- Thromboangiitis obliterans (Buerger's disease) particularly affects young tobacco smokers, causing severe digital ischemia and ulceration 6
- Atherosclerotic peripheral arterial disease produces digital ulcers in older patients with cardiovascular risk factors 6
- Thromboembolic disease (both macro- and microembolic) occludes digital vessels 6
Prothrombotic States
Multiple hematologic abnormalities predispose to digital ulceration through microvascular thrombosis 6:
- Protein C, protein S, or antithrombin III deficiencies
- Factor V Leiden or prothrombin gene mutations
- Hyperhomocysteinemia
- Antiphospholipid antibodies (lupus anticoagulant, anticardiolipin antibodies)
- Malignancy-associated hypercoagulable states
- Inflammatory bowel disease-related thrombophilia
Occupational and Environmental Causes
- Chronic cold exposure damages digital vessels through repeated vasospastic injury 6
- Vibration injury from power tools causes traumatic vasculopathy (hand-arm vibration syndrome) 6
- Radiation-associated arteritis develops months to years after therapeutic radiation 6
Drug-Induced Digital Ulcers
Several medications cause digital ischemia and ulceration 6:
- Ergot alkaloids produce severe vasospasm
- Bleomycin causes vascular toxicity
- Clonidine induces vasoconstriction
- Beta-blockers may precipitate digital ischemia in susceptible patients
Mechanical and Trauma-Related Causes
In diabetic patients, digital ulcers arise from different mechanisms 1:
- Hammertoe deformities with flexible toe contractures create pressure points on digit apices and plantar surfaces
- Neuropathic ulceration from loss of protective sensation combined with repetitive trauma
- These ulcers heal in 97% of cases within 29.5 days when the underlying deformity is surgically corrected 1
Risk Factors Within Systemic Sclerosis
When digital ulcers occur in SSc patients, specific features predict higher risk 3, 4, 5:
- Male gender (stronger association than in female patients)
- Younger age at SSc diagnosis (earlier disease onset correlates with ulcer development)
- Diffuse cutaneous subtype (higher risk than limited cutaneous SSc)
- Anti-topoisomerase I (anti-Scl70) antibody positivity (OR 2.15)
- Higher modified Rodnan skin scores (reflecting more severe skin fibrosis)
- Impaired DLCO on pulmonary function testing
- Presence of other peripheral vascular manifestations: Raynaud's phenomenon, telangiectasias, acro-osteolysis, calcinosis cutis
- Puffy fingers (OR 2.82)
- Higher disease activity scores (revEUSTAR-AI; OR 6.63)
Associated Complications and Prognostic Implications
Digital ulcers in SSc associate with worse outcomes 3:
- Interstitial lung disease occurs more frequently in patients with digital ulcer history
- Calcinosis cutis shows strong association with digital ulceration
- Reduced survival across all SSc cutaneous subsets, particularly notable in limited cutaneous SSc and SSc sine scleroderma
- Gangrene develops in 22.5% of SSc digital ulcer cases 7
- Osteomyelitis complicates 11% of SSc digital ulcers 7
Critical Pitfall to Avoid
Do not assume all digital ulcers in SSc patients are purely ischemic. 1 While vasculopathy dominates, infection and trauma contribute significantly. Each ulcer requires assessment for infection (requiring antibiotics), ischemia severity (determining urgency of vascular intervention), and mechanical factors (necessitating offloading or surgical correction). Missing superimposed infection or critical ischemia with impending gangrene delays life-saving interventions.