What are the causes of chronic leg ulcers?

Major Causes of Chronic Leg Ulcers

Chronic leg ulcers are primarily caused by venous insufficiency (65%), arterial disease (10%), or a combination of both (10%), with other etiologies accounting for the remaining cases. 1

Vascular Causes

1. Venous Insufficiency

• Most common cause (65% of all leg ulcers) 2, 1
• Pathophysiology: Primary valvular incompetence or post-thrombotic syndrome leading to venous hypertension 2
• Characteristics:
  • Location: Medial malleolus or "gaiter" area of lower leg
  • Appearance: Shallow, irregular margins, often with surrounding hyperpigmentation
  • Associated findings: Edema, varicosities, lipodermatosclerosis, atrophie blanche

2. Arterial Disease

• Accounts for approximately 10% of leg ulcers 1, 3
• Pathophysiology: Atherosclerosis leading to reduced arterial blood flow 2
• Characteristics:
  • Location: Toes, foot, lateral malleolus
  • Appearance: Well-demarcated, "punched out" appearance
  • Associated findings: Pain (especially at rest), pallor on elevation, dependent rubor, absent pulses
  • Diagnostic indicators: Ankle-brachial index <0.6, toe pressures <50 mmHg, TcPO₂ <30 mmHg 2

3. Mixed Venous-Arterial Disease

• Accounts for approximately 10% of leg ulcers 3
• Features of both venous and arterial insufficiency
• Requires careful assessment as compression therapy may be contraindicated or modified

Neuropathic Causes

4. Diabetic Neuropathy

• Accounts for approximately 5% of leg ulcers 3
• Often affects the foot rather than leg
• Pathophysiology: Sensory neuropathy leading to unrecognized trauma 2
• Characteristics:
  • Location: Pressure points (metatarsal heads, heel)
  • Appearance: Callused edges, deep
  • Associated findings: Decreased sensation, foot deformities, history of diabetes

Inflammatory/Autoimmune Causes

5. Vasculitis

• Small vessel inflammation causing tissue ischemia 2
• Associated with autoimmune diseases (rheumatoid arthritis, systemic lupus erythematosus)
• Characteristics:
  • Multiple, painful ulcers
  • Palpable purpura may precede ulceration

6. Pyoderma Gangrenosum

• Neutrophilic dermatosis often associated with inflammatory bowel disease, rheumatoid arthritis 2
• Characteristics:
  • Rapid progression
  • Violaceous undermined borders
  • Extreme pain disproportionate to appearance

Metabolic/Hematologic Causes

7. Calciphylaxis

• Vascular calcification in chronic kidney disease 3
• Extremely painful, stellate ulcers with surrounding livedo reticularis

8. Antiphospholipid Syndrome

• Hypercoagulable state causing microvascular thrombosis 3
• Characteristics: Livedo reticularis, painful ulcers

Infectious Causes

9. Bacterial Infections

• Primary or secondary infection
• Common pathogens: Staphylococcus aureus, Pseudomonas, beta-hemolytic streptococci
• May complicate existing ulcers or cause primary ulceration

Malignant Causes

10. Skin Malignancies

• Basal cell carcinoma, squamous cell carcinoma, melanoma
• May present as non-healing ulcers or develop in chronic wounds (Marjolin's ulcer)
• Characteristics: Raised, rolled edges, irregular borders, tissue friability

11. Martorell Hypertensive Leg Ulcer

• Associated with poorly controlled hypertension 3
• Extremely painful ulcers on the lateral aspect of the lower leg

Medication-Related Causes

12. Hydroxyurea

• Can cause painful leg ulcers in patients on long-term therapy
• Typically lateral malleolar location

13. Coumarin Necrosis

• Rare complication of warfarin therapy 3
• Occurs within days of initiating treatment

Traumatic/Factitious Causes

14. Pressure Ulcers

• Prolonged pressure over bony prominences
• Common in immobile patients

15. Factitious Ulcers

• Self-induced wounds
• Bizarre shapes, unusual locations, resistant to standard therapies

Evaluation Approach

1. Comprehensive vascular assessment:

   • Palpation of pedal pulses
   • Ankle-brachial index (ABI)
   • Toe pressures or transcutaneous oxygen measurements when indicated 2

2. Ulcer characteristics:

   • Location, size, depth, appearance of wound bed
   • Border characteristics (regular, irregular, undermined)
   • Surrounding skin changes (pigmentation, edema, induration)

3. Diagnostic testing when etiology unclear:

   • Wound biopsy (for suspected malignancy or vasculitis)
   • Blood tests (complete blood count, inflammatory markers, autoimmune panels)
   • Vascular imaging studies (duplex ultrasound, angiography)

Management Principles

Management must address the underlying cause:

• Venous ulcers: Compression therapy is cornerstone of treatment 2
• Arterial ulcers: Revascularization should be considered 2
• Diabetic ulcers: Offloading pressure, glycemic control, infection management 2
• Inflammatory ulcers: Immunosuppressive therapy based on specific diagnosis 2

Remember that proper diagnosis is essential, as treatment approaches differ significantly based on etiology. Many chronic leg ulcers have multiple contributing factors requiring a multidisciplinary approach to management.