Ulcer

What is it?

An ulcer is a deep, open wound in the skin where both the outer layer (epidermis) and the deeper layer (dermis) have been lost, creating a crater-like defect. Unlike an erosion, which is superficial and heals without a trace, an ulcer extends below the basement membrane and typically heals with scarring. Skin ulcers can result from poor blood circulation (venous or arterial disease), nerve damage (diabetic neuropathy), prolonged pressure, infection, autoimmune conditions, or even cancer. Chronic ulcers (those lasting more than 4-6 weeks) are a significant medical problem affecting quality of life.

What does it look like?

Ulcers have characteristic features that help identify their cause:

• Depth: Extends into the dermis or deeper — a visible crater or defect in the skin
• Base: May show healthy pink granulation tissue (healing), yellow slough (fibrin debris), or black necrotic tissue (dead tissue)
• Edges: Can be sloping (venous ulcer), punched-out (arterial ulcer), undermined (pyoderma gangrenosum), or rolled/raised (malignant ulcer)
• Shape: Round, oval, irregular, or serpiginous (snake-like)
• Size: From a few millimeters to very large (encompassing the entire lower leg)
• Discharge: May produce serous fluid, blood, or pus
• Surrounding skin: May show changes characteristic of the underlying cause

Where does it appear?

Ulcer location often points to the underlying cause:

• Medial lower leg (inner ankle area): Venous ulcers — the most common type, associated with venous insufficiency, varicose veins, leg swelling, and brownish skin discoloration
• Toes, foot, lateral ankle: Arterial ulcers — associated with peripheral artery disease, absent foot pulses, cold feet, and pain that worsens when lying down
• Weight-bearing areas of the foot: Diabetic (neuropathic) ulcers — over pressure points in patients with reduced foot sensation
• Sacrum, heels, bony prominences: Pressure ulcers — in immobilized or bedridden patients
• Lower legs (atypical locations): Pyoderma gangrenosum — rapidly expanding, painful ulcer with violaceous undermined borders
• Any sun-exposed skin: Malignant ulcer — non-healing ulcer that may represent squamous cell carcinoma

Associated features

Ulcers may be accompanied by:

• Pain — varies by cause: severe in arterial ulcers, often minimal in neuropathic ulcers
• Surrounding skin changes — hemosiderin staining and lipodermatosclerosis (venous), pallor and hair loss (arterial)
• Discharge or odor — suggests infection or necrosis
• Slow healing — chronic ulcers may persist for months or years
• Repeated recurrence after healing — especially venous ulcers
• Swelling (edema) of the affected limb
• Fever or systemic symptoms if infection is present

When to see a doctor

Seek prompt medical evaluation for:

• Any wound that does not heal within 4-6 weeks
• A rapidly expanding, painful ulcer (possible pyoderma gangrenosum — may worsen with surgery)
• An ulcer with raised, rolled, or hard edges (possible skin cancer — biopsy needed)
• Signs of infection: increasing pain, warmth, redness, pus, fever, red streaks
• Ulcer with exposed bone, tendon, or deep tissue
• New ulcers in patients with diabetes, vascular disease, or immunosuppression
• Any non-healing ulcer needs evaluation to exclude malignancy (Marjolin ulcer — cancer developing in a chronic wound)