Erythema multiforme

Erythema multiforme


Erythema multiforme is a skin condition of
unknown cause, possibly mediated by deposition of immune complex in the superficial microvasculature
of the skin and oral mucous membrane that usually follows an infection or drug exposure. It is an uncommon disorder, with peak incidence
in the second and third decades of life. Presentation
The condition varies from a mild, self-limited rash to a severe, life-threatening form known
as erythema multiforme major that also involves mucous membranes. Consensus classification:
Erythema multiforme minor – Typical targets or raised, edematous papules distributed acrally
Erythema multiforme major – Typical targets or raised, edematous papules distributed acrally
with involvement of one or more mucous membranes; epidermal detachment involves less than 10%
of total body surface area SJS/TEN – Widespread blisters predominant
on the trunk and face, presenting with erythematous or pruritic macules and one or more mucous
membrane erosions; epidermal detachment is less than 10% TBSA for Stevens-Johnson syndrome
and 30% or more for toxic epidermal necrolysis. The mild form usually presents with mildly
itchy, pink-red blotches, symmetrically arranged and starting on the extremities. It often takes on the classical “target lesion”
appearance, with a pink-red ring around a pale center. Resolution within 7–10 days is the norm. Individuals with persistent erythema multiforme
will often have a lesion form at an injury site, e.g. a minor scratch or abrasion, within
a week. Irritation or even pressure from clothing
will cause the erythema sore to continue to expand along its margins for weeks or months,
long after the original sore at the center heals. Causes Many suspected aetiologic factors have been
reported to cause EM. Infections: Bacterial vaccination, haemolytic
Streptococci, legionellosis, leprosy, Neisseria meningitidis, Mycobacterium, Pneumococcus,
Salmonella species, Staphylococcus species, Mycoplasma pneumoniae), Chlamydial. Fungal
Parasitic, Viral
Drug reactions, most commonly to: Antibiotics, anticonvulsants, aspirin, antituberculoids,
and allopurinol and many others. Physical factors – Radiotherapy, cold, sunlight
Others – Collagen diseases, vasculitides, non-Hodgkin lymphoma, leukaemia, multiple
myeloma, myeloid metaplasia, polycythemia EM minor is regarded as being triggered by
HSV in almost all cases. A herpetic aetiology also accounts for 55%
of cases of EM major. Among the other infections, Mycoplasma infection
appears to be a common cause. Herpes simplex virus suppression and even
prophylaxis has been shown to prevent recurrent erythema multiforme eruption. The human form of orf can also cause erythema
multiforme. Treatment
Erythema multiforme is frequently self-limiting and requires no treatment. The appropriateness of glucocorticoid therapy
can be uncertain, because it is difficult to determine if the course will be a resolving
one. See also
Erythema multiforme major Erythema multiforme minor
Toxic epidermal necrolysis Stevens–Johnson syndrome
References

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