Erythema multiformeErythema multiforme is a skin reaction that results in red, target-shaped patches on the skin. Erythema multiforme is an hypersensitivity reaction commonly caused by an infection or a medication. The person's body responds to an organism or chemical with an exaggerated allergic response. Erythema multiforme can be minor or more severe. The more severe form is also known as Stevens-Johnson syndrome. Severe reactions can involve the skin, lungs, kidneys, eyes, and other areas.
Rarely, in severe cases, death may occur.
Erythema multiforme (EM) is an acute, self-limiting, inflammatory skin eruption. 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. Erythema multiforme typically affects teenagers and young adults, but onset may be as late as 50 years or more of age. Toxic epidermal necrolysis typically occurs in older individuals. There is a male predilection, although toxic epidermal necrolysis shows a rather strong female predilection. Skin or mucosal lesions occur abruptly and may be rather localized or may cover most of the body surfaces. Oral lesions tend to affect the labial and buccal mucosa, but any mucosal surface may be involved, although lesions of the gingiva and hard palate are rare. Fever, lymphadenopathy, malaise, headache, cough, sore throat, and polyarthralgia may present as prodromal signs and symptom as much as a week prior to the onset of the surface erythema or blisters. On the skin, a wide variety of irregular red macular, papular and vesicular lesions may occur, either separately or in combination. A unique lesion, the target or bull's-eye lesion appears as concentric rings of affected skin interspersed with rings of clinically normal skin, often with a bullous lesion at the center.
Cases called to the attention of the dental profession often present with only oral involvement or oral and conjunctival involvement. Whether alone or in conjunction with dermal disease, oral lesions begin as erythematous macules which go on to form bullae with irregular outlines and a strong inflammatory halo. Blisters readily rupture to leave a flat white ulcer bed. The erythema which may be the only manifestation of skin involvement is less pronounced when it occurs in the mouth and often it is not present at all. Some patients experience only shallow ulceration, not bullous formation. Bullous and ulcerative oral lesions are moderately painful or tender, and this is usually the patient's main complaint, but severe involvement, such as that seen in toxic epidermal necrolysis, may lead to sloughing of large portions of the oral mucosa, giving the patient the appearance of having been badly scalded. Secondary infection of skin lesions may cause additional destruction or septicemia. Significant ocular scaring and synechiae formation occurs in half of affected patients from bullous lesions of the conjunctiva, often with loss of eye lashes and perhaps with fusion of the bulbar and lid conjunctivae.
Treatment of Erythema multiforme begins with identification and removal of the trigger factor, however that is not always possible. EM minor is typically asymptomatic and therefore needs no treatment, as the lesions will clear up by themselves within 2-4 weeks. In herpes virus induced EM minor, Zovirax or Valtrex pills will help, but only if started in the first few days. If the EM keeps recurring, a continuous low dose of Zovirax or Valtrex will prevent it. Systemic therapy to treat SJS used to be limited to supportive measures, such as placement in a burn unit. We now know that if caught early, intravenous Cytoxan, pooled gamma globulin or oral cyclosporin are dramatically helpful. An older treatment, oral steroids (such as prednisone) also is still useful in some cases. It should not be used because when given to with patients with severe mouth and throat sores, it causes them to succumb more readily to fatal respiratory infections. For a fully developed case of SJS, transfer to a burn unit still may be needed.