Erythema is a broad category of skin condition that can impact any area of the skin and mucous membranes. It usually occurs in response to disease or infection in reaction to a drug. Severity of the rash ranges from mild to life threatening.
What Is Erythema?
Erythema is an abnormal redness of skin or mucous membranes. Capillary congestion causes the condition, and red splotches on the hands or feet are classic examples of it.
People often mistake erythema for common skin inflammation or psoriasis because it has similar characteristics: redness, rashes, swelling and skin sensitivity.
Although it most commonly presents on the skin and mucous membranes, erythema can appear on all parts of the body in various patterns and colors. A variety of factors, including skin tone and blood flow, influence Erythema’s color. Some forms of the rash may cause blisters that burst and lead to sores.
Two major categories of erythema diagnoses are: erythema multiforme and erythema nodosum. Each brings a different treatment approach.
Erythema multiforme (EM) is the most common type of erythema. Its cause is thought to be IgM immune complexes deposited in the skin, often as a result of viral or bacterial infections, such as herpes simplex virus (HSV) type 1 and 2 and Mycoplasma pneumoniae infections. More rarely, it can be a reaction to a drug or vaccine, according to the National Library of Medicine.
The condition can affect both men and women, although men are five times more likely to develop it compared to women. Most people who get EM are between 20 and 30 years old, although 20% of those diagnosed are children.
There are two types of EM, minor and major.
Erythema multiforme minor (EM minor) typically occurs on the peripheral parts of the body, such as the fingers and toes. Rarely, it may manifest as light mouth sores. It usually clears up on its own.
Erythema multiforme major (EM major) skin lesions are more extensive and serious. Raised, edematous papules covering more than 10% of the body with involvement of at least one mucous membrane characterizes the condition. A drug reaction is a more likely cause than an infection. Similarly, medication also causes Stevens-Johnson Syndrome, a potentially life-threatening skin rash.
Unlike EM minor, EM major causes extensive blistering sores on one or more of the body’s mucous membranes, such as the lips or mouth.. They can also appear on the eyes or anus. If you are experiencing irritation or what appears to be blistering on one of these areas of your body, you should contact your doctor.
Most people with EM develop a sudden small rash that usually begins on their feet or hands and spreads to the upper limbs, face and upper body. It starts with small red spots that grow larger and form what looks to be a bull’s-eye, darker in the middle with a lighter outer ring.
- Circular red bumps on the soles, palms, arms, face and legs that grow into circles that may look like targets.
- Itchiness, in some cases.
- Painful sores or blisters on the lips, mouth, eyes and genitals.
- Red patches with pale rings inside the patch with purple centers and small blisters, called target lesions.
- Joint pain.
- Sensitivity to light.
The rash may itch and grow uncomfortable, and it can last up to four weeks before dissipating. Severe cases are rare. When they occur, patches of rash cluster together and form painful areas of raw skin. If you are experiencing one or more of these symptoms, be sure to contact your doctor.
The treatment for erythema multiforme depends on the subtype. EM minor usually goes away on its own, but if symptoms persist, a doctor might recommend topical steroids. If EM minor symptoms recur because of a suspected herpes flare-up, doctors may prescribe antiviral medications such as acyclovir or valacyclovir.
The presence of EM can also be a sign of a more serious condition or a compromise of the immune system. When your doctor examines you, they may choose to recommend additional testing.
Those diagnosed with EM major may require more care. Aside from steroids, eye drops and mouthwashes with topical anesthetics, they may need to be admitted to a hospital for IV fluids.
About 80% of erythema cases are erythema nodosum, making it the most common type of this skin infection. Like erythema multiforme, causes of erythema nodosum include certain medications, such as birth control pills, sulfa-related drugs, estrogens and viral, fungal and bacterial infections. Common infections linked to the condition include cat scratch disease, infectious mononucleosis, Behcet’s disease, inflammatory bowel diseases and sarcoidosis.
Erythema nodosum mostly appears on the front of the legs or just below the knee. Defining hallmarks are lumps that range in size from that of a dime to a quarter.
The condition usually disappears on its own in three to six weeks. However, there are cases of chronic erythema nodosum in which lesions appear on a different body part.
Symptoms of erythema nodosum come on suddenly and usually initially present as hot, symmetrical nodules on the ankles, knees and legs.
- Red, tender bumps on the shin.
- Joint pain.
- Enlarged chest lymph nodes.
Together, symptoms mimic those of inflammatory bowel diseases, cancer, bacterial and fungal infections and diseases such as tuberculosis. Because of these close associations, doctors must be meticulous in their diagnostic process.
Treatment approaches for erythema nodosum differ based on the person’s age and overall health, medical history, medication and therapy tolerance, and progression of the disease. Usual options are anti-inflammatory drugs such as NSAIDs and cortisone, either administered orally or through injections.
While the condition can be painful, it does not compromise internal organs. It may, however, be an indication of more serious conditions.
Be on the lookout for erythema signs and symptoms. If you have skin inflammation, consult a doctor who can rule out the skin infection or provide the best course of action.
Disease-Related Types of Erythema
Like EM and EN, which both can result from bacterial and viral infections, some forms of erythema stem from underlying diseases or illnesses. Examples are Lyme disease and rheumatic fever. Some erythema breakouts are signs of complex illnesses such as liver disease, diabetes and thyroid diseases.
The disease-related types are erythema infectiosum (fifth disease), erythema chronicum migrans, erythema marginatum and palmar erythema. Unlike EM and EN, these are not allergic reactions to medications.
Fifth disease is common in children, while other types are rare. Doctors try to control the skin conditions based on how much they itch or cause pain, but they usually treat the underlying disease.
Fifth disease is a mild and common rash in children. Parvovirus B19 causes the condition, which typically presents within 14 days of the parvovirus infection. Sometimes called a “slapped-cheek” rash because it first shows up on the sides of the face, the rash may spread from the face to the neck, chest, buttocks, legs, arms or feet.
Symptoms include fever, headache and runny nose. Some people may have joint pain that lasts one to three weeks, but other symptoms typically go away within seven to 10 days of treatment, which includes supportive care to relieve itching, fever and swelling.
Fifth disease can last for months or longer, but it doesn’t cause long-term problems.
Erythema Chronicum Migrans
The bite of an infected tick causes erythema chronicum migrans, or erythema migrans. This skin rash occurs in 70% to 80% of people infected with Lyme disease.
The rash begins at the site of the tick bite between three and 30 days after the bite. As it expands, the rash forms a red spot with a bigger red ring surrounding it, similar in appearance to a bull’s-eye. Sometimes it appears as a red patch with central hardening and blistering.
Erythema migrans can be sensitive, warm to the touch and itchy, but it rarely causes any pain. Symptoms include fever, chills, headaches and body aches, particularly in the joints. For treatment, doctors focus on the Lyme disease and any itching that surfaces.
Erythema marginatum is a rare skin rash that usually develops in response to rheumatic fever, although other causes include Lyme disease, allergic reactions to drugs and hereditary angioedema. It typically presents on the body’s trunk and limbs.
The rash can appear with a pale, pink center and a darker red outline and is not usually painful or itchy. It fades without treatment, but doctors could prescribe medications for any underlying diseases.
Palmar erythema presents as a painless red rash on the palms and sometimes on the fingers of both hands. Although it doesn’t itch, it can get redder with changes in temperature, pressure on the palm, emotional states or hand elevation.
There are two types of palmar erythema. Primary palmar erythema stems from pregnancy, occurring in about 30% of expectant mothers. Family history of the disease and unknown allergies are also factors.
Autoimmune diseases such as rheumatoid arthritis or lupus, diabetes, cancer, chronic obstructive lung disease, liver disease, thyrotoxicosis or a reaction to medications cause secondary palmar erythema. Doctors can perform diagnostic tests to check for an underlying internal disorder as a potential cause.
Environmental and Unknown Causes of Erythema
Two types of erythema, erythema toxicum and erythema annulare centrifugum, have no known causes. Overexposure to one of several heat sources causes a third type, erythema ab igne.
Erythema Ab Igne
Repeated exposure to infrared radiation or direct heat to the skin causes erythema ab igne. Heat sources include warm water bottles, heating pads, laptop computers and space heaters.
Lesions appear as mild pink patches that turn red or violet, then brown. Patches form lace-like or fishnet patterns and can itch, burn and cause pain. Treatment consists of removing the offending heat source.
Mild cases abate in a few months, but more advanced cases may linger for years or be permanent. In these cases, treatment includes tretinoin, 5-fluorouracil or laser therapy to improve appearance.
In rare cases, erythema ab igne leads to cancer. A dermatologist should monitor the rash and may recommend a biopsy for long-lasting rashes.
Erythema toxicum, also known as erythema toxicum neonatorum, affects 40% to 70% of full-term newborns. It sometimes occurs at birth, but most infants show signs in their second or third day of life.
It appears as a rash of white or yellow papules with blotchy red patches surrounding it. Erythema toxicum usually occurs on the trunk, face and extremities. Papules may have noninfectious fluid in them.
The condition typically fades over five to seven days without treatment. It can recur but usually not after the infant is 4 months old.
Erythema Annulare Centrifugum (EAC)
A lesion of tiny red bumps that spread from a central patch of skin characterizes erythema annulare centrifugum, or EAC. They may form irregular shapes, but more often they form a circular, ring-like pattern.
EAC is more common than erythema ab igne and erythema toxicum. It most often affects the legs, particularly the thighs. It is more likely to occur in middle age, but some parents have reported the rash on infants.
Doctors usually treat it with topical corticosteroids, topical antipruritic creams or sedating antihistamines.
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