Erythema Multiforme Major

February 8, 2017

Erythema multiforme is a hypersensitivity reaction usually triggered by infections, most commonly herpes simplex virus (HSV). It presents with a skin eruption characterised by a typical target lesion. There may be mucous membrane involvement. It is acute and self-limiting, usually resolving without complications.

Erythema multiforme has 2 forms –

Erythema multiforme minor—most common, is generally mild and may go away on its own, and usually caused by a virus
Erythema multiforme major—rare, usually more severe, less likely go away on its own, and usually caused by medications

A variety of factors have been implicated in the pathogenesis of EM. The disorder is most commonly induced by infection, with herpes simplex virus being the most frequent precipitator. The clinical course of EM is usually self-limited, resolving within weeks without significant sequelae. However, in a minority of cases, the disease recurs frequently over the course of years.

The rash is made of spots that are red welts, sometimes with purple or blistered areas in the center. It often also affects the mouth, eyes and other moist surfaces. Erythema multiforme has been so named because of the “multiple forms” it appears in; there is a large degree of variety in its clinical presentation. This variation has led to EM being divided into two overlapping subgroups (EM minor and Stevens-Johnson syndrome). These are different faces of the same disease.

EM is relatively common problem for a dermatologist. Half the cases are in young people (under 20). It rare both under the age of 3 and over the age of 50. Males are slightly more affected than females and there is no racial predilection. One third of EM sufferers will have a recurrence of the disease. Seasonal epidemics are common.

Causes

It is thought that erythema multiforme is caused by damage to tissues and blood vessels on the skin. This may result from infection with the herpes simplex virus, infection with mycoplasma bacteria, or a reaction to a medication. Minor cases of erythema multiform are more commonly associated with a herpes simplex infection, whereas severe cases are more commonly associated with reactions to medication.

The herpes simplex virus that causes erythema multiforme is also responsible for cold sores. The virus can lie dormant unless activated by a trigger that causes a flare-up. Some people may develop a cold sore in the days before a rash appears.

Severe erythema multiforme is most often caused by a reaction to certain types of medications. Penicillin antibiotics such as amoxicillin and ampicillin, anticonvulsants, barbiturates, sulphonamides, tetracyclines, and non-steroidal anti-inflammatory drugs (NSAIDs) have all been known to cause erythema multiforme.

Risk Factors

Factors that may increase the chance of getting erythema multiforme include –

History of erythema multiforme

Infection or history of infection caused by –

Virus—herpes infection is the main cause in erythema multiforme minor
Bacteria
Fungus
Parasite

Certain medications (usual cause of erythema multiforme major), such as –

Antibacterials
Anticonvulsants
Non-steroidal anti-inflammatory drugs

Certain vaccinations including –

Diptheria and tetanus vaccine
Hepatitis B vaccine
Smallpox vaccine

Symptoms

Symptoms of erythema multiforme include –

Fever
General ill feeling
Itchy skin
Joint aches
Multiple skin lesions (sores or abnormal areas)

Skin sores may –

Start quickly
Come back
Spread
Be raised or discolored
Look like hives
Have a central sore surrounded by pale red rings, also called a target, iris, or bulls-eye
Have liquid-filled bumps or blisters of various sizes
Be located on the upper body, legs, arms, palms, hands, or feet
Include the face or lips
Appear evenly on both sides of the body (symmetrical)

Other symptoms may include –

Bloodshot eyes
Dry eyes
Eye burning, itching, and discharge
Eye pain
Mouth sores
Vision problems

Complications

Some complications of erythema multiforme are –

Body-wide infection (sepsis)
Loss of body fluids (shock)
Lesions on internal organs, causing inflammation of the heart (myocarditis), lung (pneumonitis), kidney (nephritis), and liver (hepatitis)
Permanent skin damage and scarring
Skin infection (cellulitis)

Treatment

Treatment of severe symptoms may include –

Antibiotics for skin infections
Corticosteroids to control inflammation
Treatment in an intensive care or burn care unit for severe cases, Stevens-Johnson syndrome, and toxic epidermal necrolysis (top layer of skin separates from the lower layers)
Intravenous immunoglobulins (IVIG, an injection of healthy cells from donors into a vein) to stop the disease process

Good hygiene and staying away from other people may help prevent secondary infections (infections that occur from treating the first infection).

Moist compresses and medications may help relieve discomfort from lesions. Medication options may include –