context: A rash indicates an abnormal change in skin color or texture. Rashes are usually caused by skin inflammation, which can have many causes. There are many types of rashes, including eczema, granuloma annulare, lichen planus, and pityriasis rosea. Eczema is a general term that describes several different conditions in which skin is inflamed, red, scaly, and itchy. Eczema is a common skin condition, and atopic dermatitis (also called atopic eczema) is one of the most common forms of eczema. Eczema can occur in adults or children. The condition is not contagious. The cause of atopic eczema is not known, but the condition often affects people with a family history of allergies. Many individuals with eczema also have hay fever and/or asthma or have family members with those conditions. Some factors can trigger a flare-up of eczema or make eczema worse, but they do not cause the condition. Eczema triggers include stress, skin irritants (including soaps, skin care products, or some fabrics), allergens, and climate/environment. The appearance of eczema can vary from person to person. In adults, eczema occurs most frequently on the hands and elbows, and in "bending" areas such as the inside of the elbows and back of the knees. In young children, eczema is often seen on the inside of elbows, behind the knees, face, back of the neck, and scalp. Signs and symptoms of atopic eczema include: Itchiness Skin redness Dry, scaly, or crusted skin that might become thick and leathery from long-term scratching Formation of small, fluid-filled blisters that might ooze when scratched Infection of the areas where the skin has been broken Atopic eczema usually is diagnosed with an analysis of a person's history of symptoms and with an exam of the skin. A doctor might test an area of scaly or crusted skin to rule out other skin diseases or infections. Atopic mineral oil can be treated with with moisturizers that are fragrance free and contain ingredients such as ceramides, glycerin, and mineral oil. Medications include over-the-counter creams and ointments containing the steroid hydrocortisone (for example, Cortizone-10, Cort- Aid, Dermarest Eczema, Neosporin Eczema). These products may help control the itching, swelling, and redness associated with eczema. Prescription-strength cortisone creams, as well as cortisone pills and shots, are also used for more severe cases of eczema. For people with mild-to-moderate eczema, topical immunomodulators ( TIMs) can help. TIMS -- including brand name products Protopic and Elidel -- work by altering the body's immune response to allergens, preventing flare ups. Crisaborole ( Eucrisa) is an ointment indicated for mild to moderate psoriasis in patients 2 and older. Dupilumab ( Dupixent) is an injectable monoclonal antibody used in patients with moderate to severe atopic dermatitis. It clears the itch quickly in most patients. Other drugs that might be used for patients with eczema include antibiotics (to treat infected skin) and antihistamines (to help control itching). Phototherapy is another treatment that helps some people with eczema. The ultraviolet light waves found in sunlight have been shown to benefit certain skin disorders, including eczema. Phototherapy uses ultraviolet light, either ultraviolet A ( UVA) or ultraviolet B ( UVB), from special lamps to treat people with severe eczema. Risks associated with phototherapy include burning (usually resembling a mild sunburn), dry skin, itchy skin, freckling, and possible premature aging of the skin. Your health care professionals will work with you to minimize any risks. Currently, there is no effective strategy for preventing atopic eczema, but the symptoms of the condition can improve. To improve the signs of eczema: Reduce stress Avoid scratchy materials (for example, wool) and chemicals such as harsh soaps, detergents, and solvents Moisturize frequently Avoid sudden changes in temperature or humidity Avoid situations that cause sweating and overheating Granuloma annulare is a chronic skin condition that consists of a circular-shaped rash with reddish bumps (papules). Most often, the condition affects children and young adults. Granuloma annulare is slightly more common in girls and usually is seen in people who are otherwise healthy. The cause of granuloma annulare is unknown. People who have granuloma annulare usually notice a ring of small, firm bumps over the backs of the forearms, hands, or feet. More than one ring may be noticed in some cases. The rash may be mildly itchy. The condition is diagnosed by a doctor who may use a skin biopsy to confirm the diagnosis. Treatment of granuloma annulare often is not necessary, except for cosmetic reasons. In some cases, steroid creams or ointments are used to help the bumps disappear. Some doctors may decide to freeze the lesions with liquid nitrogen or to inject steroids directly into the rings of bumps. Ultraviolet light therapy or oral drugs can be used in severe cases. Lichen planus is a common skin disorder that produces shiny, flat-topped bumps that often have an angular shape and a reddish-purplish color. Lichen planus can occur anywhere on the skin but is often found on the insides of the wrists and ankles, the lower legs, the back, and the neck. Some people have lichen planus inside their mouth, genital region, scalp, and nails. Thick collections of bumps may occur, especially on the shins. Lichen planus occurs most often in adults aged 30 to 70. It is not common in very young or elderly people. Lichen planus is believed to be an autoimmune process where the body's immune system attacks its own tissues. In most cases, the cause of lichen planus is not known. When lichen planus is thought to be caused by a triggering agent such as hepatitis B or C, it is known as a lichenoid reaction. Medications to treat high blood pressure, heart disease, and arthritis can cause lichen planus-type rashes that are allergic reactions to those drugs. Lichen planus is not contagious. Signs and symptoms of the condition include shiny, flat-topped bumps that are purple or a reddish-purplish color, and it is often itchy. When it appears on the scalp, lichen planus may cause hair loss. Lichen planus of the nails can cause brittle or split nails. A doctor can diagnose lichen planus by its distinctive appearance or with the use of a skin biopsy. In a skin biopsy, a small bit of skin is taken from the affected area and is sent to a lab for testing. Although lichen planus cannot be cured, its symptoms can be treated with anti-itch products such as antihistamines (for example, Benadryl, or diphenhydramine). If lichen planus affects only a small part of the body, medicated cream can be applied to the affected area. Drugs such as steroid injections, prednisone, other drugs to suppress the immune system, or retinoids may be prescribed in more severe cases. Another treatment for lichen planus is light therapy. Talk to your doctor about which treatment is right for you. Pityriasis rosea is a common skin rash that usually is mild. The condition often begins with a large, scaly, pink patch of skin on the chest or back. The patch usually is followed by additional pink patches of skin. There is itching and redness or inflammation of the skin. The number and sizes of the spots can vary. The cause of pityriasis rosea is not known. However, there is evidence that suggests pityriasis rosea may be caused by a virus because the rash resembles certain viral illnesses. The rash does not seem to spread from person to person. The primary symptom of pityriasis rosea is large, scaly, pink area of skin that is followed by additional skin lesions. The spots become itchy and there may be redness or inflammation of the skin. Pityriasis rosea affects the back, neck, chest, abdomen, upper arms, and legs, but the rash may differ from person to person. A doctor can usually diagnose pityriasis rosea by looking at it. He or she may order blood tests, scrape the skin, or do a skin biopsy to rule out other skin conditions. Treatment may not be necessary in mild cases of pityriasis rosea, and even more severe cases can go away without treatment. Oral antihistamines (for example Benadryl or diphenhydramine) and topical over-the-counter medications or prescription steroids can help soothe itching. Sores may heal faster with some exposure to sunlight or ultraviolet light. Too much sun exposure should be avoided, however. In most cases, pityriasis rosea goes away within six to 12 weeks.