A skin lesion is any area of skin with an abnormal appearance or growth compared to the surrounding tissue. Many are a normal part of life, while others can indicate a health issue. This guide provides information to help identify various lesions, but a dermatologist should evaluate any new, changing, or concerning spot.
Common Benign Skin Lesions
Many skin growths are benign, meaning they are non-cancerous and harmless. Common moles, technically known as nevi, are pigmented spots that can be flat or raised and are usually smaller than 6mm. Most moles are harmless and maintain a consistent size, shape, and color.
Skin tags, or acrochordons, are small, soft, flesh-colored growths that hang from the skin by a thin stalk. They commonly develop in areas where skin rubs against skin, such as the neck, armpits, and under the breasts. Skin tags are composed of collagen fibers and blood vessels and are painless unless irritated by friction.
Cherry angiomas are also common, appearing as small, bright red or purple spots. These lesions are made of dilated blood vessels and can be flat or slightly raised. They often appear on the torso, arms, and legs, and their frequency increases after age 30. They are linked to aging and genetics and are considered harmless.
Seborrheic keratoses are growths that often look “pasted on” the skin. Their appearance can be waxy or scaly, with a color ranging from light tan to black. These lesions appear on the face, chest, shoulders, or back and become more common with age. They are benign and do not become cancerous.
Lesions Caused by Infections or Inflammation
Some skin lesions are reactions to pathogens or internal inflammation. Warts are caused by the human papillomavirus (HPV). They are rough to the touch and may have small black pinpoints, which are clotted blood vessels. Warts can appear anywhere on the body but are commonly found on the hands and feet.
Fungal infections can also manifest as skin lesions. Ringworm, for example, is caused by a fungus and appears as a red, scaly, ring-shaped patch that can be itchy. The center of the ring may appear clear as the fungus expands outward. This lesion is contagious and spreads through direct contact.
Inflammatory conditions like eczema and psoriasis result from an overactive immune response. Eczema presents as dry, itchy, and inflamed patches of skin that may weep clear fluid when scratched. Psoriasis is characterized by thick, red, scaly patches from an accumulation of excess skin cells. These conditions are not contagious but represent chronic underlying inflammation.
Potentially Cancerous Skin Growths
Certain skin growths have the potential to be cancerous and require prompt medical evaluation. Basal cell carcinoma (BCC) is the most common type of skin cancer. It often appears as a pearly or waxy bump, sometimes with visible blood vessels, or as a flat, flesh-colored or brown scar-like lesion. These growths frequently occur on sun-exposed areas like the face and neck.
Squamous cell carcinoma (SCC) is the second most common form and also tends to develop on skin that receives significant sun exposure. It might present as a firm, red nodule or a flat lesion with a scaly, crusted surface. An SCC can grow quickly and may bleed if irritated. Early detection is important to prevent it from spreading.
Melanoma is a less common but more aggressive form of skin cancer that develops in the melanocytes, the cells that produce pigment. It can arise from an existing mole or appear as a new spot. Because melanoma can spread to other organs if not treated early, it is the most dangerous type of skin cancer.
The ABCDE Guide for Melanoma Evaluation
The ABCDE guide is a structured method for examining moles and other pigmented spots for signs of melanoma. Each letter represents a feature to watch for, contrasting with the characteristics of a benign mole.
- A is for Asymmetry: One half of the lesion does not match the other half. Benign moles are symmetrical.
- B is for Border: The edges of an early melanoma are uneven, scalloped, or notched, while a benign mole has smooth borders.
- C is for Color: The presence of multiple colors, such as shades of brown, black, tan, or even red or blue, is a warning sign. Benign moles are a single shade of brown.
- D is for Diameter: Melanomas are often larger than 6 millimeters (about the size of a pencil eraser) when diagnosed, although they can be smaller.
- E is for Evolving: Any change in a mole’s size, shape, color, or elevation, or any new symptom like bleeding or crusting, points to danger.
When to Consult a Dermatologist
Professional evaluation is necessary for any concerning skin lesion, as self-diagnosis is not reliable. A visit to a dermatologist is recommended if you notice any new spot or if an existing spot changes or shows ABCDE characteristics. Other red flags include a sore that does not heal within a few weeks, or one that bleeds, oozes, or becomes crusty. A spot that is persistently itchy or painful should also be examined, as early detection improves outcomes for skin cancer.