Macules are flat, non-palpable lesions that usually measure less than 10 mm in diameter. They represent a change in color and are not uneven from the skin’s surface (neither raised nor depressed).
Papules are raised lesions that are usually less than 10 mm in diameter that can be felt. Some examples are moles, warts, lichen planus, insect bites, seborrheic and actinic keratoses, some acne lesions, and skin cancers.
Plaques are palpable lesions that usually measure more than 10 mm in diameter and are elevated or depressed compared to the skin surface. The plaques can have a flat or domed roof. Psoriasis lesions and granuloma annulare usually form plaques.
Nodules are firm papules or lesions that extend into the dermis or subcutaneous tissue. Some examples are cysts, lipomas, and fibroids.
The vesicles are small blisters and filled with a clear liquid, they are less than 10 mm in diameter. They are small elevations of the skin.
The ampoules contain a clear liquid and their diameter is more than 10 mm. They can be caused by burns, stings, allergic contact or irritant dermatitis, and drug reactions.
Pustules are pus-containing vesicles. They are frequent in bacterial infections and folliculitis and can appear in some inflammatory disorders such as pustular psoriasis.
Urticaria (hives or welts) is characterized by the presence of elevated lesions caused by localized edema. The welts are itchy and red. Wheals are a frequent manifestation of drug hypersensitivity, stings or bites, autoimmunity, or, less frequently, reactions to physical stimuli such as temperature, pressure, and sunlight.
Scales are accumulations of cornified epithelium that are seen in diseases such as psoriasis, seborrheic dermatitis, and fungal infections. Pityriasis rosea and chronic dermatitis of any kind can flake.
Scabs are made up of dried serum, blood, or pus. Its presence may be due to inflammatory or infectious skin diseases, for example, impetigo.
Erosions are open areas of the skin as a result of the loss of part or all of the epidermis. They can be traumatic or occur in different inflammatory or infectious skin diseases. A galling is a linear erosion caused by scratches, friction, or scratching.
Ulcers are caused by loss of the epidermis and at least part of the dermis. Causes include, without venous stasis dermatitis, physical trauma with vascular involvement (caused by pressure ulcers or peripheral arterial disease), infections, and vasculitis.
Petechiae are pinpoint hemorrhage foci that do not disappear on vitropressure. Causes include platelet abnormalities (thrombocytopenia, platelet dysfunction), vasculitis, and infections.
Purple is a large area of bleeding that can be palpable. It may indicate the presence of a coagulopathy. Large areas of purple may be called ecchymosis or, colloquially, bruising.
Atrophy is thinning of the skin, which can appear dry and wrinkled, similar to the role of cigarettes. Atrophy can be caused by chronic exposure to sunlight, aging, and some neoplastic and inflammatory skin diseases. It can also be the result of prolonged use of powerful topical corticosteroids.
Scars are areas of fibrosis that replace normal skin after injury. Some scars become hypertrophic or thickened and elevated. Keloids are hypertrophic scars that extend beyond the original wound margins.
Telangiectasias are permanently dilated foci of small blood vessels that can appear in sun-damaged areas, rosacea. In systemic diseases, in hereditary diseases or after prolonged treatment with topical fluorinated corticosteroids.