A skin ulcer is an open sore that develops when damaged skin fails to heal, often extending through the full thickness of the epidermis and into the deeper layer of the dermis or beyond. An ulcer is a persistent wound that does not follow the normal healing process. These lesions are commonly caused by underlying issues like poor blood circulation or prolonged pressure, which prevent the skin tissue from receiving the necessary oxygen and nutrients. Recognizing the visual characteristics of a skin ulcer is the first step toward seeking appropriate medical care.
General Appearance and Location
A skin ulcer typically presents as a crater-like depression in the skin, where tissue has disintegrated. The overall shape is often described as circular or irregular, with the base of the wound exposed. Depending on the severity and tissue type, the base color can vary greatly, ranging from a healthy red or pink of granulation tissue to a yellow or gray color from non-viable tissue called slough. The edges of the ulcer may appear thick and raised, sometimes described as rolled, particularly in chronic wounds. Ulcers often occur over bony prominences where pressure is concentrated, or on the lower extremities due to circulatory issues. Common locations include the heels, ankles, hips, and buttocks. The surrounding skin may also show discoloration, appearing red, warm, or even shiny and blue in darker skin tones, indicating inflammation or poor blood flow.
Visual Signatures of Common Ulcer Types
Pressure Ulcers
Pressure ulcers, also known as bedsores, develop when continuous pressure on an area restricts blood flow to the tissue over a bony prominence. They are frequently seen on the heels, ankles, hips, and tailbone. Early signs may only be a persistent, non-blanching red or purple patch of skin. As the ulcer deepens, it takes on a more defined crater appearance, and the wound base may contain black or dark brown necrotic tissue called eschar. The depth can vary significantly, from shallow wounds to deep ulcers that expose muscle or tendon.
Venous Ulcers
Venous ulcers result from chronic venous insufficiency, where malfunctioning valves allow blood to pool and increase pressure in the veins of the lower leg. These are the most common type of leg ulcer, typically forming in the “gaiter area,” just above the ankle on the inner side of the lower leg. Venous ulcers are generally shallow, with an irregular, gently sloping border, and can be quite large. The wound base is often moist or “weepy” due to heavy fluid drainage, and may be covered in yellow slough or bright red granulation tissue. A distinct visual sign is the surrounding skin, which often exhibits brown or purple discoloration, known as hemosiderin staining. The skin around the wound may also look scaly, thick, and feel warm to the touch.
Arterial Ulcers
Arterial ulcers, or ischemic ulcers, occur due to blocked arteries that restrict the delivery of oxygen-rich blood to the tissue. These ulcers are found on the toes, feet, heels, and bony prominences of the ankle. They typically have a characteristic “punched-out” appearance, meaning they are deep with regular, well-defined, and sometimes raised borders. The wound base appears pale, gray, or yellowish, lacking the red, healthy appearance of granulation tissue due to poor oxygenation. Arterial ulcers usually have minimal drainage, making them appear dry. The surrounding skin is pale, cool to the touch, shiny, and may be hairless, reflecting diminished circulation.
Recognizing Signs of Worsening or Infection
Visual changes in an ulcer can signal that the wound is deteriorating or has become infected. A spreading area of redness, or erythema, that extends beyond the wound border and into the surrounding healthy skin is a common sign of a spreading infection. The area may also feel noticeably warmer to the touch than the rest of the limb. Infection often causes a change in the wound’s discharge; it may become thick, cloudy, or change color to yellow or green, which is indicative of pus. A sudden, foul odor emanating from the wound is another sensory cue. Other signs of worsening include a rapid increase in the ulcer’s size or depth, or the development of new, dark-colored, hard eschar.
When to Seek Medical Attention
Any skin sore that fails to show clear signs of healing within two to three weeks warrants medical evaluation. If an ulcer is deep, growing rapidly, or causing increasing pain, a healthcare provider should be consulted. Immediate medical attention is necessary if the ulcer shows any signs of infection, such as fever, chills, spreading redness, unusual or foul-smelling discharge, or warmth. A healthcare professional is needed to determine the ulcer’s type, assess its severity, and address the underlying cause.