What Is Erythema Marginatum?
Erythema marginatum is a rare skin rash that spreads on the trunk and limbs. The rash is round, with a pale-pink center, surrounded by a slightly raised red outline. The rash can appear in rings or have less regular, larger, or elongated shapes.
The rash isn’t a disease in itself. Rather, it can be a symptom of an underlying condition, such as:
- rheumatic fever
- hereditary angioedema
- Lyme disease
- allergic reaction
There are several other kinds of erythema rashes besides erythema marginatum. These include:
- erythema migrans, which tends to stay in one place on the body
- erythema multiforme lesions, which can spread over the body and appear as raised, crusty patches
- erythema annular centrifugum, which can be itchy and scaly, and may appear on the face
These rashes are only connected by the term “erythema”, which means “red.” They each have distinctive characteristics and causes that are otherwise unrelated.
Read on to learn more about erythema marginatum.
Identifying erythema marginatum rash
The erythema marginatum rash can look like a faint pattern on your skin with a pinkish center, and a flat or slightly raised red border. The overall shape can be regular rings or semicircles, or less regular shapes with wavy margins.
Erythema marginatum fades in and out over time. It may appear only for hours, or for days or longer. The rash isn’t itchy or painful, and it may not be noticeable on darker skin tones.
Erythema marginatum appears mostly on the trunk and limbs. It doesn’t usually appear on the face.
Picture of erythema marginatum
Causes of this rash
There are several conditions that can cause erythema marginatum rash.
- joint pain
- nodules under the skin
- heart valve damage
- elevated C-reactive protein in the blood
- other skin rashes
Rheumatic fever is a complication from strep throat that isn’t adequately treated with antibiotics. It can lead to serious heart damage. The disease is very rare in the United States now, with an occurrence of 0.04–0.06 cases per 1,000 children. Rheumatic fever and rheumatic heart disease (RHD) are more frequently seen in underdeveloped countries. There are an estimated 15 million cases of RHD worldwide.
Erythema marginatum may be an early sign of hereditary angioedema. The rash occurs in about 42 to 58 per cent of children with a type of hereditary angioedema referred to as C1-INH-HAE, including newborns.
This rare inherited disease occurs in about 1 in 50,000 people. Symptoms often don’t appear until after puberty.
The erythema marginatum rash can be important as a warning of an upcoming attack. Sometimes the rash is misdiagnosed as hives, delaying testing for angioedema.
Other symptoms include:
- swelling of the face, hands, arms, and legs
- gastrointestinal problems
Rarely, erythema marginatum can be one of the skin symptoms of Lyme disease, though erythema migrans is more commonly seen with this condition.
Lyme is an often-debilitating disease transmitted by Borrelia burgdorferi bacteria via black-legged deer ticks. It’s difficult to diagnose because of its wide range of symptoms mimics those of many diseases.
- achy, stiff, or swollen joints
- headache, fever, dizziness, and other flu-like symptoms
- night sweats and sleep disturbances
- cognitive decline
- neurological problems
Adverse reactions to certain drugs can produce an erythema marginatum rash. For example, the combination antibiotic amoxicillin-clavulanate (Augmentin) can cause erythema marginatum.
Diagnosing the cause of erythema marginatum
If you or your child has a rash that looks like erythema marginatum, see a doctor. The rash is not dangerous in itself but could indicate a serious underlying condition.
Your doctor will ask about your medical history, medications you are taking, and other symptoms.
If you’ve recently had strep throat, your doctor may order blood tests to look for markers of rheumatic fever. They may also do tests to check for heart damage. There is no one test to diagnose rheumatic fever.
Your doctor may also order blood tests if inherited angioedema is suspected to check for decreased C1 inhibitor, which is a sign of the condition.
Lyme is often diagnosed on the basis of symptoms and a blood test.
Treating the underlying causes of the rash
There’s no treatment for erythema marginatum. The rash fades on its own. You may need to be treated for an underlying condition responsible for the rash.
Rheumatic fever is treated with:
- antibiotics for infection
- salicylates for arthritic symptoms
- corticosteroids for heart involvement
Inherited angioedema is treated with C1 esterase inhibitor (Cinryze) or icatibant (Firazyr).
Lyme is treated with antibiotics.
The illnesses that commonly cause erythema marginatum are rare in developed countries, and therefore this rash isn’t often seen in the United States. Other, similar rashes are more common and can be confused with erythema marginatum. It’s important to see your doctor for an accurate diagnosis.
The erythema marginatum rash fades out on its own over time, sometimes in hours. It can be a symptom of various underlying conditions, but usually rheumatic fever. If you have inherited angioedema, the rash may return as a forewarning of an attack.
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