Erythema Multiforme, Emergency Medicine

Basics

Description

A rash caused by a hypersensitivity reaction:
- May occur in response to various medications, infections, or other illness
Erythema multiforme (EM) minor:
- Typical target lesions
- Edematous papules
- Usually distributed peripherally
- Benign, self-limited rash generally not associated with acute, serious illness
EM major
- Also called bullous EM
- Target lesions
- Edematous papules
- Also with peripheral distribution
- Involves 1 or more mucous membranes
- <10% total body surface area of epidermal detachment
Differentiate from:
- Stevens-Johnson syndrome (SJS):
  - Also <10% TBSA epidermal detachment
  - Often widespread blisters over trunk and face
  - Mucosal involvement
- Toxic epidermal necrolysis (TEN)
  - >30% TBSA epidermal detachment
- EM is now considered a different entity from SJS and EM
Most often affects children and young adults (>50% younger than 20 yr)
Males are affected more often than females.

Etiology

Hypersensitivity reaction, probably transient autoimmune defect
Herpes simplex virus (HSV) is the most common precipitant (>70%).
Other causes include:
- Idiopathic
- Medications
  - Penicillin
  - Sulfur based
  - Phenytoin
  - Barbiturates
  - NSAIDs
- Vaccines
  - Diphtheria-tetanus
  - Hepatitis B
  - Smallpox
- Malignancy
- Infection
  - HIV
  - CMV
  - Hepatitis C
  - Mycoplasma infections

Diagnosis

Signs and Symptoms

History

Prodrome: Infrequent systemic symptoms (mild fever/malaise), antecedent HSV in most cases (within 3 wk)
Usually not associated with severe systemic illness

Physical Exam
Characteristic rash:

Lesions:
- Symmetric dull red macules and papules
- Evolve into round, well-demarcated target lesions with central clearing
- No epidermal necrosis with EM minor
Multiforme refers to the evolution of the rash through various stages at different times.
Distribution:
- Extremities
- Dorsal hands and feet
- Extensor surfaces
- Elbows and knees.
1 of the few rashes that may involve palms and soles
Spread: From extremities toward trunk
Mucosal involvement: Minor blistering or erosions of 1 mucosal surface (lips/mouth)
Duration: Usually 1-4 wk, but may become chronic or recurrent

Essential Workup

Complete history and physical exam, with special attention to the skin, genitourinary system, recent infectious symptoms, and recent medications

Diagnosis Tests & Interpretation

Lab
No specific lab tests needed
Imaging
No specific imaging is helpful.
Diagnostic Procedures/Surgery

Skin biopsy reveals mononuclear cell infiltrate around upper dermal blood vessels, without leukocytoclastic vasculitis and necrosis of epidermal keratinocytes.
Biopsy is not necessary in most cases.

Differential Diagnosis

Systemic lupus erythematosus
Fixed drug eruption
Pityriasis rosea
Secondary syphilis
Erythema migrans
Urticaria
SJS
TEN
Vasculitis
Viral exanthem

Treatment

Pre-Hospital

Not contagious and does not require isolation or postexposure prophylaxis for exposed personnel

Initial Stabilization/Therapy

Generally benign and self-limited, requiring no initial stabilization

Ed Treatment/Procedures

Attempt to identify, treat, or remove underlying cause or precipitant.
Symptomatic: Cool compresses, antipruritics

Medication

Antiviral agents:
- Acute EM
- Treat within 48 hr of onset
- May not impact clinical course
  - Acyclovir: 400 mg PO TID
Prevention of recurrent EM
- Acyclovir 400 mg PO BID
- Valacyclovir 500 mg PO BID
- Famciclovir 250 mg PO BID
Antipruritic agents:
- Cetirizine (Zyrtec): 10 mg/d (peds: 2.5-5 mg) PO
- Diphenhydramine: 25-50 mg (peds: 5 mg/kg/24h) PO q6-8h
- Hydroxyzine: 25 mg PO q6-8h (peds: 2 mg/kg/24h div. q6-8h)
Anesthetic for oral lesions
- Magic mouthwash
Oral corticosteroids:
- Reserved for severe mucosal disease
- Prednisone 40-60 mg PO QD tapered over 2-3 wk
Medium-potency topical corticosteroids:
- Triamcinolone 1% apply BID-QID
  - Do not use on face or eyelids
Low-potency topical corticosteroids
- For face or intertriginous regions
- Hydrocortisone 1% apply BID-QID

First Line

Topical corticosteroids (low to medium potency)
Antipruritics

Second Line

Antivirals
Oral corticosteroids

Follow-Up

Disposition

Admission Criteria

Admission is not needed unless required for another concurrent disorder.
Unable to take PO fluids secondary to mucosal lesions

Discharge Criteria
EM is generally a benign disorder that does not require admission.
Issues for Referral

Patients should be referred to a dermatologist if the diagnosis is uncertain or the rash is atypical or severe.
Refer immediately to ophthalmologist if ocular involvement

Follow-Up Recommendations

Follow-up with primary care physician within 1 wk to assess:
- Further evaluation of underlying conditions (infection, medications, malignancy, etc.)
- Progression or resolution of rash
Follow-up with a dermatologist within 1 wk if the diagnosis is uncertain.

Pearls and Pitfalls

In patients with severe systemic illness, a more serious diagnosis should be considered, such as SJS or TEN.
Most patients with EM have underlying HSV infection.
Secondary syphilis may produce similar lesions on the palms and soles.
Reassure patients that the rash of EM is benign and self-limited.

Additional Reading

Dyall-Smith D. Erythema multiforme. Available at www.dermnetnz.org. Accessed on July 1, 2011.
Lamoreux MR, Sternbach MR, Hsu WT. Erythema multiforme. Am Fam Physician. 2006;74:1883-1888.
Plaza J. Erythema multiforme. Available at www.emedicine.com. Accessed on July 29, 2011.
Scully C, Bagan J. Oral mucosal diseases: Erythema multiforme. Br J Oral Maxillofac Surg. 2008;46:90-95.
Sokumbi O, Wetter DA. Clinical features, diagnosis, and treatment of erythema multiforme: A review for the practicing dermatologist. Int J Dermatol. 2012;51:889-902.
Wetter DA. Pathogenesis, clinical features, and diagnosis of erythema multiforme. In: Callen J, ed. UpToDate. Waltham, MA: UpToDate; 2013.
Wetter DA. Treatment of erythema multiforme. In: Callen J, ed. UpToDate. Waltham, MA: UpToDate; 2013.

Codes

ICD9

695.10 Erythema multiforme, unspecified
695.13 Stevens-Johnson syndrome
695.15 Toxic epidermal necrolysis
695.19 Other erythema multiforme
695.11 Erythema multiforme minor
695.12 Erythema multiforme major
695.14 Stevens-Johnson syndrome-toxic epidermal necrolysis overlap syndrome
695.1 Erythema multiforme

ICD10

L51.1 Stevens-Johnson syndrome
L51.2 Toxic epidermal necrolysis [Lyell]
L51.9 Erythema multiforme, unspecified
L51.8 Other erythema multiforme
L51.3 Stevens-Johnson synd-tox epdrml necrolysis overlap syndrome

SNOMED

36715001 erythema multiforme (disorder)
73442001 Stevens-Johnson syndrome (disorder)
23067006 Lyells toxic epidermal necrolysis, subepidermal type (disorder)
297942002 Drug-induced erythema multiforme (disorder)
402971008 Erythema multiforme due to mycoplasma infection (disorder)

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