Primary Causes of Leg Ulcers
The primary causes of leg ulcers are venous insufficiency (approximately 80%), arterial insufficiency, neuropathy (particularly in diabetes), or a combination of these etiologies, with less common causes including malignancy, autoimmune diseases, and infections. 1
Major Etiological Categories
1. Venous Ulcers (65-80% of all leg ulcers)
- Result from chronic venous insufficiency and venous hypertension 2
- Typically occur on the medial aspect of the lower leg, particularly around the ankle
- Characteristics:
- Shallow with irregular borders
- Often have surrounding hyperpigmentation and lipodermatosclerosis
- May have varicose veins visible in the affected leg
- Usually painless or pain improves with elevation
2. Arterial Ulcers (10-15% of all leg ulcers)
- Caused by peripheral arterial disease (PAD) leading to tissue ischemia 3
- Typically found on toes, feet, or lateral ankle
- Characteristics:
- Well-demarcated, "punched out" appearance
- Pale wound bed with minimal granulation
- Severe pain, especially at night and with elevation
- Diminished or absent pedal pulses
- Delayed capillary refill time
3. Diabetic/Neuropathic Ulcers (5% of leg ulcers)
- Result from peripheral neuropathy with or without PAD 2
- Typically occur on pressure points of the foot (metatarsal heads, heels)
- Characteristics:
- Painless due to sensory neuropathy
- Often surrounded by callus formation
- May have deep penetration to bone
4. Mixed Etiology Ulcers (10-20% of leg ulcers)
- Combined venous and arterial insufficiency 4
- Characteristics of both venous and arterial ulcers
- More challenging to treat due to competing management strategies
Less Common Causes
5. Infectious Ulcers
- Bacterial, fungal, or mycobacterial infections
- May be primary or secondary infection of existing ulcers
6. Malignancy
- Primary skin cancers (squamous cell carcinoma, basal cell carcinoma)
- Malignant transformation of chronic ulcers (Marjolin's ulcer)
- Cutaneous manifestations of systemic malignancies
7. Autoimmune/Inflammatory Conditions
- Vasculitis (e.g., polyarteritis nodosa, rheumatoid arthritis)
- Pyoderma gangrenosum
- Necrobiosis lipoidica
8. Hematological Disorders
- Sickle cell disease
- Polycythemia vera
- Thrombophilia
9. Medication-Induced
- Hydroxyurea
- Coumarin necrosis
- Chemotherapeutic agents
Diagnostic Approach
When evaluating leg ulcers, assessment should include:
Vascular assessment:
- Palpation of pedal pulses
- Ankle-brachial pressure index (ABI)
- Toe pressures or transcutaneous oxygen pressure (TcPO₂) if ABI is falsely elevated 2
Neurological assessment:
- Monofilament testing for protective sensation
- Vibration perception using 128-Hz tuning fork
- Pin-prick and tactile sensation 2
Ulcer characteristics:
- Location, size, depth, appearance
- Presence of necrotic tissue, exudate, surrounding skin changes
- Signs of infection (redness, warmth, pain, purulent discharge) 2
Clinical Pearls and Pitfalls
- Don't assume etiology based solely on appearance: While certain characteristics suggest specific etiologies, definitive diagnosis requires comprehensive assessment.
- Consider mixed etiology: Many patients have multiple contributing factors.
- Beware of malignancy: Chronic non-healing ulcers should raise suspicion for malignancy and may require biopsy.
- Look beyond the ulcer: The underlying cause must be addressed for successful healing.
- Ill-fitting footwear is a common cause of ulceration, even in patients with "pure" ischemic ulcers 2
Understanding the primary cause of leg ulcers is essential for implementing appropriate treatment strategies and achieving optimal outcomes in terms of healing, preventing recurrence, and maintaining quality of life.