A leg ulcer is a chronic, open sore on the lower leg or foot that fails to heal naturally, typically persisting for more than four to six weeks. Ulcers are not a disease themselves but a symptom of an underlying medical condition, usually involving poor circulation or nerve damage. Poor circulation prevents the delivery of necessary oxygen and nutrients, while nerve damage can lead to undetected injury. Understanding the visual characteristics of a leg ulcer is the first step toward identifying the root cause for effective treatment.
General Appearance and Characteristics
Chronic leg ulcers share several visual attributes despite their varying origins. The size can range from a small, shallow pit to an extensive wound covering a large patch of the lower leg. Depth also varies, sometimes affecting only the superficial skin layers, and at other times extending deep into the subcutaneous tissue.
The borders of the ulcer can be a distinguishing feature, presenting as either irregularly sloped or sharply defined and “punched out.” The wound bed may show new tissue growth, appearing as wet, reddish-pink granulation tissue. Alternatively, the bed may contain dead tissue, such as yellow slough or a black, hard scab called eschar. Most ulcers produce fluid drainage, or exudate, which varies from minimal dampness to a heavy, weeping flow.
Visual Distinctions Between Major Ulcer Types
The visual presentation of a leg ulcer is often the clearest indicator of its cause, most commonly distinguishing between venous and arterial issues. Venous ulcers, which account for the majority of chronic leg wounds, are caused by high pressure in the veins due to faulty valves, leading to blood pooling. They typically present as wide, shallow wounds with sloping and irregular edges.
The wound bed of a venous ulcer is often a vibrant red, reflecting healthy granulation tissue. It tends to be moist with moderate to heavy amounts of exudate. These ulcers are most frequently located in the “gaiter area,” the inner part of the leg just above the ankle bone (medial malleolus), where venous hypertension is most pronounced.
Arterial ulcers arise from a lack of blood flow due to narrowed or blocked arteries, resulting in tissue starvation. Visually, these ulcers have a distinct “punched out” appearance, featuring smooth, well-defined, and often circular borders. Because of the lack of blood supply, the wound bed is often pale, yellow, or black from necrosis, and it is characteristically dry with minimal drainage. Arterial ulcers typically appear on the feet, toes, heels, or at sites of trauma or pressure.
Appearance of Ulcers Related to Nerve Damage
Ulcers related to nerve damage, known as neuropathic ulcers, are common in individuals with diabetes who have lost sensation in their feet. The absence of pain means minor injuries or continuous pressure go unnoticed, leading to tissue breakdown. These ulcers primarily occur on the sole or plantar surface of the foot, specifically over weight-bearing bony prominences like the ball of the foot or the heel.
A defining characteristic of a neuropathic ulcer is the presence of thick, hard, calloused skin (hyperkeratosis) surrounding the wound. The ulcer may look minor on the surface, often circular and small, but it is frequently deep, tunneling into the foot due to underlying pressure and trauma. The wound bed can be pink or contain slough, and the true extent of tissue damage is often hidden beneath the thick callus.
Surrounding Skin Changes and Signs of Infection
Beyond the wound, the surrounding skin provides important clues about the underlying problem. With venous disease, the skin around the ankle and lower leg may be swollen (edema), and often exhibits reddish-brown discoloration known as hemosiderin staining. This staining occurs when red blood cells leak out of compromised veins and deposit iron pigment in the tissue.
Conversely, skin changes associated with arterial disease include a thin, shiny, and hairless appearance due to poor nourishment. The affected leg may also feel cool to the touch due to reduced blood flow. These non-ulcerative changes help distinguish the vascular cause.
The presence of an active infection requires immediate attention and presents with specific visual warning signs. A spreading area of redness (erythema) around the ulcer, known as cellulitis, indicates the infection is moving into the surrounding tissue. Other signs include excessive warmth, a sudden increase in pain, and drainage changing to a thick, yellow, or green pus accompanied by a foul odor. Prompt medical evaluation is necessary if these signs are observed.