What is the diagnosis?
Erythema multiforme major
Define erythema multiforme.
Acute, self-limiting but often relapsing, mucocutaneous inflammatory condition.
It is a hypersensitivity reaction associated with certain infections, vaccinations and sometimes medications.
It forms target lesions - annular erythematous rings.
How common is erythema multiforme?
Affects any age group
Most commonly children and young adults
M:F ratio 2:1
What is the pathophysiology of erythema multiforme?
Cell mediated immune response (type II or IV)
Degeneration of basal epidermal cells and development of vesicles between the cells and the underlying basement membrane
Lymphocytic infiltrate is seen around blood vessels and at the DEJ
Immune complex deposition is variable and non specific.
Precipitating factor found in 50% of cases
List 5 broad causes of erythema multiforme.
Infection - viral: HSV(1>2), EBV, coxsackie, adenovirus, ORF. Bacterial: mycoplasma pneumoniae, chlamydiae. Fungal: histoplasmosis.
Drugs (<10%)- sulphonamides, peniciillin, phenytoim, barbituates
Inflammatory -RA, SLE, sarcoid, UC, systemic vasculitis
Malignancy - lymphomas, leukaemia, myeloma
Radiotherapy
Which cause of EM is most common?
Infectious cause > drugs
What are the risk factors for erythema multiforme?
- Proir occurrence
- HSV infection
- Mycoplasma pnuemonia
- CMV
- EBV
- Hep B or vaccine
- Histoplasmosis
- HIV
- lympphoma
- orf virus infection
- medication
- tattoo
- syphilis
What can be found in a history associated with erythema multiforme?
Prodromal symptoms of URTI
Sudden appearance of itching/burning/painful skin lesions which may fade leaving behind pigmentation.
Lesions appear over 3-5days
What are the signs of erythema multiforme?
- Target lesions of the extremities moving centrally
- Bull’s eye lesions - 3 zones: red rim, clearance zone, central blister or erosion.
- Targetoid lesions - erythematous papules without the clearance zone are more common centripetally.
- Mucosal involvement (in EM major)- oropharynx, lips, conjunctivae, genitalia; lesions are vesicles which then show erosions
- Rapid onset of lesions
- Lungs - ronchi, rales +/- wheezes if mycoplasma pneumonia
- Red tympanic membranes - suggest mycoplasma pneumonia
- Fever, myalgia, malaise
- Painful , pruritic
- Symmetrical lesions distributed over arms and legs including palms and soles
What is the difference between major and minor erythema multiforme?
Major involved mucocutaneous surface
What investigations should you do for erythema multiforme?
Clinical diagnosis
Also:
- Skin biopsy - histology and direct immunofluorescence may be indicated in cases of diagnostic doubt.
- Viral and wound swab
- HSV and mycoplasma serology
- FBC, U&Es, LFTs - raised WCC, eosinophils, ESR, CRP, low albumin in extensive exudation, raised urea (catabolic state and dehydration), autoantibodies
- Imaging - CXR (exclude sarcoid and atypical pneumonias)
What are the complications of erythema multiforme?
- Secondary bacterial infection
- Oral lip scarring (microstomia)
Ocular involvement has more serious complications:
- Blindness in 10-30% if cornea affected
How do you manage erythema multiforme?
Symptomatic: Episodes are self-limiting without complications
- Antihistamines - for itching and
- NSAIDs
- Treat underlying cause - e.g. infection, medications stopped
- Mouth wash
- Ophthalmology - if eye involvement
- IV fluids/nutrition
- Use of systemic corticosteroids is controversial
Recurrent disease: oral acyclovir for 6 months
EM major: hospital admission, ITU, denuded areas treated like burns.
Usually resolves in 2-5 weeks
What is the difference between EM major and SJS?
EM major has lesions which are raised and typical bull’s eye appearance
What is the prognosis with EM?
Most lesions heal without scarring but hypopigmentation may persist for several months
Ocular involvement has worse prognosis
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Cellulitis and Erysipelas17
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CMV18
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HSV16
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HIV31
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Infectious mononucleosis16
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Malaria16
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Neutropenic sepsis12
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Erythema multiforme15
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Necrotising fasciitis13
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Psoriasis31
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Chlamydia12
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Gonorrhoea11
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COVID-1912
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General dermatology28
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Toxic shock syndrome9
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Typhoid fever12
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Varicella Zoster16
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[6] Urinary Tract Infections42
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[8] Glomerulonephritis100
