American Medical Association Family Medical Guide - American Medical Association [96]
Actinic keratoses
Actinic keratoses (see page 1069) are small wartlike growths that develop on sun-exposed areas of the body. They are not actually skin cancer but must always be removed because they can become cancerous.
Epidermal cysts
Epidermal cysts (see page 1070), also called sebaceous cysts, usually appear as soft, smooth, sometimes yellowish lumps just beneath the surface of the skin. Sometimes a small dark dot can be seen in the skin over the center of the cyst. Epidermal cysts usually occur on the scalp, face, neck, or ears. They are harmless but can grow large and can become infected.
Keloids
When skin is injured, the damage is repaired by scar tissue. Keloids (see page 1071) are raised, hard, itchy scars caused by an abnormality in the healing process. Keloids are more common in dark-skinned people.
Boils Boils are infected hair follicles that start as red lumps under the skin and gradually become bigger and more painful as they swell with pus.
Hives
Hives (see page 1066) usually take the form of one or more raised, red, itchy patches of skin called wheals that have clearly defined edges. They are caused by allergic reactions to food, medication, cosmetics, or heat or cold. Hives usually disappear after a few hours but can recur.
Dermatographism
Dermatographism is an allergic reaction that is activated when the skin is scratched or otherwise touched with a finger or object. The resulting marks are hives that follow exactly where the skin has been touched. The red, raised, itchy patches (wheals) from these types of hives may not appear immediately and can develop up to several hours after the skin was touched.
Infections and Inflammatory Conditions
Pityriasis rosea
Pityriasis rosea (see page 1071) usually starts as one or two oval patches (left) called herald patches on the chest (right) or back. Over a few weeks, similar (usually smaller) patches appear and may spread to the upper arms and the thighs. The rash is sometimes itchy and may have a slightly scaly surface and appear orangish red in people with light skin and dark brown in people with dark skin.
Ringworm
Ringworm is a tinea (a fungus) infection (see page 1073) that is marked by red, itchy, ring-shaped rashes. The characteristic rings form when the fungus spreads uniformly outward, leaving normal skin in the center.
Psoriasis
Psoriasis (see page 1064) consists of patches of thick, raised skin that are pink or red and covered with silverish white scales. Small patches may join to form larger patches. In rare cases, the affected area can be slightly itchy or sore. Common sites for psoriasis are the knees (left), elbows, and scalp (right). When psoriasis affects the head, lumps can appear on the scalp and temporary hair loss can occur. Psoriasis can also affect the nails.
Athlete’s foot
Athlete’s foot is a tinea (a fungus) infection (see page 1073) that causes itchy, cracked skin on the feet, usually between and under the toes. The skin may peel away and occasionally blister.
Rosacea
In rosacea (see page 1066), the face (usually the skin on the cheeks and nose) becomes abnormally red and flushed, and pus-filled pimples develop on the affected areas. In some cases, the nose becomes large and bulbous and the eyes become red.
Systemic lupus
Systemic lupus erythematosus (see page 920) is a chronic disease that causes inflammation of connective tissues such as tendons and cartilage. Systemic lupus causes a red, itchy, butterfly-shaped rash over the cheeks and the bridge of the nose.
Discoid lupus
Discoid lupus erythematosus, the more common form of lupus (see page 1072), affects exposed areas of skin. In discoid lupus, the rash starts as red, circular areas of thick skin, usually on the face, behind the ears, and on the scalp. The affected area may eventually scar.
Shingles
Shingles (see page 936), caused by the herpes zoster virus, usually appears as a rash around an eye (left) or