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Emergency And Acute Medicine - Erythema multiforme
Basic description
Erythema multiforme is a rash caused by a hypersensitivity reaction that may occur in response to medications, infections, or other illnesses.
Erythema multiforme minor is characterized by typical target lesions and edematous papules, usually distributed peripherally. It is a benign, self-limited condition and is generally not associated with serious acute illness.
Erythema multiforme major, also referred to as bullous erythema multiforme, presents with similar target lesions and edematous papules in a peripheral distribution but includes involvement of one or more mucous membranes with less than 10% total body surface area epidermal detachment.
It is important to differentiate erythema multiforme from Stevens–Johnson syndrome, which also involves less than 10% total body surface area epidermal detachment but typically presents with more widespread blistering over the trunk and face and prominent mucosal involvement, and from toxic epidermal necrolysis, which involves more than 30% total body surface area detachment.
Erythema multiforme is now considered a distinct entity separate from Stevens–Johnson syndrome and toxic epidermal necrolysis. It most commonly affects children and young adults, with more than half of cases occurring in patients younger than 20 years. Males are affected more often than females.
Etiology
Erythema multiforme is a hypersensitivity reaction, likely related to a transient autoimmune defect. Herpes simplex virus is the most common precipitating factor, accounting for more than 70% of cases. Other causes include idiopathic disease, medications such as penicillins, sulfa-based drugs, phenytoin, barbiturates, and NSAIDs, vaccines including diphtheria–tetanus, hepatitis B, and smallpox, as well as malignancy and infections such as HIV, cytomegalovirus, hepatitis C, and Mycoplasma infections.
Diagnosis – signs and symptoms
Patients may have a mild prodrome with low-grade fever or malaise, although systemic symptoms are infrequent. A history of antecedent herpes simplex infection within three weeks is common. The condition is usually not associated with severe systemic illness.
Physical examination
The characteristic rash consists of symmetric dull red macules and papules that evolve into round, well-demarcated target lesions with central clearing. There is no epidermal necrosis in erythema multiforme minor. The term “multiforme” reflects the presence of lesions at various stages of evolution simultaneously.
Lesions are typically distributed on the extremities, especially the dorsal hands and feet, extensor surfaces, elbows, and knees, and erythema multiforme is one of the few rashes that may involve the palms and soles. The rash often spreads from the extremities toward the trunk.
Mucosal involvement, when present, usually consists of minor blistering or erosions affecting a single mucosal surface, most commonly the lips or oral cavity. The duration of illness is usually one to four weeks, although recurrent or chronic cases may occur.
Essential workup
Evaluation consists of a complete history and physical examination, with particular attention to skin findings, recent infections, medication exposure, and genitourinary involvement.
Diagnosis tests and interpretation
No specific laboratory tests or imaging studies are required. Skin biopsy, when performed, shows a mononuclear cell infiltrate around superficial dermal blood vessels without leukocytoclastic vasculitis or epidermal keratinocyte necrosis. Biopsy is not necessary in most cases.
Differential diagnosis
Systemic lupus erythematosus, fixed drug eruption, pityriasis rosea, secondary syphilis, erythema migrans, urticaria, viral exanthem, vasculitis, Stevens–Johnson syndrome, and toxic epidermal necrolysis.
Treatment
Prehospital care
Erythema multiforme is not contagious and does not require isolation or postexposure prophylaxis.
Initial stabilization and therapy
The condition is generally benign and self-limited and does not require acute stabilization.
Emergency department treatment and procedures
Management focuses on identifying and removing the underlying cause when possible. Treatment is primarily symptomatic and includes cool compresses and antipruritic measures.
Medication
Antiviral therapy may be considered in acute herpes-associated erythema multiforme if initiated within 48 hours of onset, although it may not significantly alter the clinical course. Acyclovir may be used for prevention of recurrent disease.
Antipruritic agents such as cetirizine, diphenhydramine, or hydroxyzine can be used for symptomatic relief.
Topical corticosteroids of low to medium potency are first-line therapy for skin lesions, with low-potency agents reserved for the face or intertriginous areas.
Oral corticosteroids are reserved for severe mucosal disease. Topical anesthetic mouth rinses may be used for painful oral lesions.
Follow-up and disposition
Admission criteria
Admission is rarely required and is generally limited to patients unable to tolerate oral intake due to severe mucosal involvement or those requiring hospitalization for another concurrent condition.
Discharge criteria
Most patients can be safely discharged, as erythema multiforme is typically a benign and self-limited disorder.
Issues for referral
Referral to dermatology is recommended if the diagnosis is uncertain or if the rash is atypical or severe. Immediate ophthalmology referral is required for any ocular involvement.
Follow-up recommendations
Patients should follow up with a primary care physician within one week to assess progression or resolution of the rash and to evaluate for underlying triggers such as infection, medications, or malignancy. Dermatology follow-up within one week is appropriate if diagnostic uncertainty remains.
Clinical pearls and common pitfalls
Severe systemic illness should prompt consideration of alternative diagnoses such as Stevens–Johnson syndrome or toxic epidermal necrolysis. Most patients with erythema multiforme have an underlying herpes simplex infection. Secondary syphilis may produce similar lesions on the palms and soles. Reassurance is important, as erythema multiforme is usually benign and self-limited.
Basic description
Erythema multiforme is a rash caused by a hypersensitivity reaction that may occur in response to medications, infections, or other illnesses.
Erythema multiforme minor is characterized by typical target lesions and edematous papules, usually distributed peripherally. It is a benign, self-limited condition and is generally not associated with serious acute illness.
Erythema multiforme major, also referred to as bullous erythema multiforme, presents with similar target lesions and edematous papules in a peripheral distribution but includes involvement of one or more mucous membranes with less than 10% total body surface area epidermal detachment.
It is important to differentiate erythema multiforme from Stevens–Johnson syndrome, which also involves less than 10% total body surface area epidermal detachment but typically presents with more widespread blistering over the trunk and face and prominent mucosal involvement, and from toxic epidermal necrolysis, which involves more than 30% total body surface area detachment.
Erythema multiforme is now considered a distinct entity separate from Stevens–Johnson syndrome and toxic epidermal necrolysis. It most commonly affects children and young adults, with more than half of cases occurring in patients younger than 20 years. Males are affected more often than females.
Etiology
Erythema multiforme is a hypersensitivity reaction, likely related to a transient autoimmune defect. Herpes simplex virus is the most common precipitating factor, accounting for more than 70% of cases. Other causes include idiopathic disease, medications such as penicillins, sulfa-based drugs, phenytoin, barbiturates, and NSAIDs, vaccines including diphtheria–tetanus, hepatitis B, and smallpox, as well as malignancy and infections such as HIV, cytomegalovirus, hepatitis C, and Mycoplasma infections.
Diagnosis – signs and symptoms
Patients may have a mild prodrome with low-grade fever or malaise, although systemic symptoms are infrequent. A history of antecedent herpes simplex infection within three weeks is common. The condition is usually not associated with severe systemic illness.
Physical examination
The characteristic rash consists of symmetric dull red macules and papules that evolve into round, well-demarcated target lesions with central clearing. There is no epidermal necrosis in erythema multiforme minor. The term “multiforme” reflects the presence of lesions at various stages of evolution simultaneously.
Lesions are typically distributed on the extremities, especially the dorsal hands and feet, extensor surfaces, elbows, and knees, and erythema multiforme is one of the few rashes that may involve the palms and soles. The rash often spreads from the extremities toward the trunk.
Mucosal involvement, when present, usually consists of minor blistering or erosions affecting a single mucosal surface, most commonly the lips or oral cavity. The duration of illness is usually one to four weeks, although recurrent or chronic cases may occur.
Essential workup
Evaluation consists of a complete history and physical examination, with particular attention to skin findings, recent infections, medication exposure, and genitourinary involvement.
Diagnosis tests and interpretation
No specific laboratory tests or imaging studies are required. Skin biopsy, when performed, shows a mononuclear cell infiltrate around superficial dermal blood vessels without leukocytoclastic vasculitis or epidermal keratinocyte necrosis. Biopsy is not necessary in most cases.
Differential diagnosis
Systemic lupus erythematosus, fixed drug eruption, pityriasis rosea, secondary syphilis, erythema migrans, urticaria, viral exanthem, vasculitis, Stevens–Johnson syndrome, and toxic epidermal necrolysis.
Treatment
Prehospital care
Erythema multiforme is not contagious and does not require isolation or postexposure prophylaxis.
Initial stabilization and therapy
The condition is generally benign and self-limited and does not require acute stabilization.
Emergency department treatment and procedures
Management focuses on identifying and removing the underlying cause when possible. Treatment is primarily symptomatic and includes cool compresses and antipruritic measures.
Medication
Antiviral therapy may be considered in acute herpes-associated erythema multiforme if initiated within 48 hours of onset, although it may not significantly alter the clinical course. Acyclovir may be used for prevention of recurrent disease.
Antipruritic agents such as cetirizine, diphenhydramine, or hydroxyzine can be used for symptomatic relief.
Topical corticosteroids of low to medium potency are first-line therapy for skin lesions, with low-potency agents reserved for the face or intertriginous areas.
Oral corticosteroids are reserved for severe mucosal disease. Topical anesthetic mouth rinses may be used for painful oral lesions.
Follow-up and disposition
Admission criteria
Admission is rarely required and is generally limited to patients unable to tolerate oral intake due to severe mucosal involvement or those requiring hospitalization for another concurrent condition.
Discharge criteria
Most patients can be safely discharged, as erythema multiforme is typically a benign and self-limited disorder.
Issues for referral
Referral to dermatology is recommended if the diagnosis is uncertain or if the rash is atypical or severe. Immediate ophthalmology referral is required for any ocular involvement.
Follow-up recommendations
Patients should follow up with a primary care physician within one week to assess progression or resolution of the rash and to evaluate for underlying triggers such as infection, medications, or malignancy. Dermatology follow-up within one week is appropriate if diagnostic uncertainty remains.
Clinical pearls and common pitfalls
Severe systemic illness should prompt consideration of alternative diagnoses such as Stevens–Johnson syndrome or toxic epidermal necrolysis. Most patients with erythema multiforme have an underlying herpes simplex infection. Secondary syphilis may produce similar lesions on the palms and soles. Reassurance is important, as erythema multiforme is usually benign and self-limited.
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