Erythema multiforme

Question 1

Define erythema multiforme.

Answer 1

Acute, self-limiting but often relapsing, mucocutaneous inflammatory condition.

It is a hypersensitivity reaction associted with certain infections, vaccinations and sometimes medications.

It forms target lesions - annular erythematous rings.

Question 2

How common is erythema multiforme?

Answer 2

Affects any age group

Most commonly children and young adults

M:F ratio 2:1

Question 3

What is the pathophysiology of erythema multiforme?

Answer 3

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 dermal-epidermal junction

Immune complex deposition is variable and non specific.

Precipitating factor found in 50% of cases

Question 4

List 5 broad causes of erythema multiforme.

Answer 4

Drugs - sulphonamides, peniciillin, phenytoim, barbituates

Infection - viral: HSV, EBV, coxsackie, adenovirus, ORF. Bacterial: mycoplasma pneumoniae, chlamydiae. Fungal: histoplasmosis.

Inflammatory -RA, SLE, sarcoid, UC, systemic vasculitis

Malignancy - lymphomas, leukaemia, myeloma

Radiotherapy

Question 5

What can be found in a history associated with erythema multiforme?

Answer 5

Prodromal symptoms of URTI

Sudden appearance of itching/burning/painful skin lesions which may fade leaving behind pigmentation.

Question 6

What are the signs of erythema multiforme?

Answer 6

• Target lesions of the extremities - 3 zones: red rim, clearance zone, central blister or erosion.
• Targetoid lesions - erythematous papules without the clearance zone(2) are more common centripetally.
• Rapid onset of lesions
• Clustered vesicles on an erythematous base - seen in HSV
• Recurrent disease - esp if HSV related
• Mucosal erosions - in EM major
• Lungs - ronchi, rales +/- wheezes if mycoplasma pneumonia
• Red tympanic membranes - suggest mycoplasma pneumonia

Rapid medicine:

“Bull’s eye” lesions with rim of erythema surrounding a paler area, vesicles/bullae, urticarial plaques.

Lesions are symmetrical, distributed over arms and legs including palms, soles and extensor surfaces

Question 7

What are the features of Stevens-Johnson syndrome?

Answer 7

_Affecting >2 mucous membrane_s - conjunctiva, cornea, lips (haemorrhagis crusts), mouth, genitalia

Systemic symptoms - sore throat, cough, fever, headache, myalgia, arthralgia, diarrhoea and vomiting

Shock - hypotension, tachycardia

This is when severe macular lesions coalesce, resulting in epidermal blistering, necrosis and sloughing - severe erythema multiforme.

Question 8

What is the difference between major and minor erythema multiforme?

Answer 8

Standard classification

Minor - Typical targets or raised oedematous papules, with acral distribution, without involvement of mucosal sites and involving <10% total body surface area.

Major - as above but WITH involvement of 1 or more mucosal sites and involving <10% total body surface area.

Question 9

What investigations should you do for erythema multiforme?

Answer 9

Clinical diagnosis so investigations usually unnecessary

To investigate precipitating factor:

• Bloods - raised WCC, eosinophils, ESR, CRP, throat swapb, serology, low albumin in extensive exudation, raised urea (catabolic state and dehydration), autoantibodies
• Imaging - CXR (exclude sarcoid and atypical pneumonias)
• Skin biopsy - histology and direct immunofluorescence may be indicated in cases of diagnostic doubt.

Question 10

What are the complications of erythema multiforme? (not on Sofia)

Answer 10

• Blindness in 10-30% if cornea affected
• Stevens-Johnson syndrome - lesions of the respiratory tract can be complicated by pneumonia and respiratory failure - mortality 5-15%

Cases caused by drugs and Mycoplasma are more likely to progress to SJ syndrome

Question 11

How do you manage erythema multiforme?

Answer 11

• Symptomatic
• Antihistamines for itching and NSAIDs for analgesia
• Treat underlying cause
• Use of systemic corticosteroids is controversial
• Oral aciclovir for recurrent episodes

SJ syndrome: ITU, denuded areas treated like burns.

Usually resolves in 2-5 weeks

Question 12

What are the risk factors for erythema multiforme?

Answer 12

• Proir occurrence
• HSV infection
• Mycoplasma pnuemonia
• CMV
• EBV
• Hep B or vaccine
• Histoplasmosis
• HIV
• lympphoma
• orf virus infection
• medication
• tattoo
• syphilis