Erythema multiforme Flashcards
Define erythema multiforme
Acute hypersensitivity reaction of skin & mucous membranes
Define Stevens-Johnson syndrome
severe form w/ bullous lesions & necrotic ulcers
Aetiology of erythema multiforme
4
Degeneration of basal epidermal cells
Development of vesicles between cells in basement membrane
Lymphocytic infiltrate around blood vessels & at derma-epidermal junction
Precipitating factor only identified 50% of time
Precipitating factors for erythema multiforme
5
Drugs - e.g. sulphonamide, penicillin, phenytoin
Infection - e.g. HSV, EBV, adenovirus, chlamydia, histoplasmosis
Inflammatory - e.g. rheumatoid arthritis, SLE, sarcoidosis, ulcerative colitis
Malignancy - e.g. lymphomas, leukaemia, myeloma
Radiotherapy
Epidemiology of erythema multiforme
age x2, gender
Any age group
Mainly children & young adults
2x more common in MALES
Presenting symptoms of erythema multiforme
3
Non-specific prodromal symptoms of upper respiratory tract infection
Sudden appearance of itching/burning/painful skin lesions
Skin lesions may fade leaving pigmentation
Signs of erythema multiforme on physical examination
4
Classic target (bull’s eye) lesion w/ rim or erythema surrounding paler area
Vesicles/bullae
Urticarial plaques
Lesions often symmetrical & distributed over arms & legs including palms, soles & extensor surfaces
Signs of Stevens-Johnson syndrome on physical examination
3
Affecting >2 mucous membranes (e.g. conjunctiva, cornea, lips, mouth, genitalia)
Systemic symptoms (e.g. sore throat, cough, fever, headache, myalgia, arthralgia, diarrhoea, vomiting)
Shock (hypotension, tachycardia)
Investigations for erythema multiforme
4
Usually unnecessary - very much a clinical diagnosis
Bloods
High WCC, eosinophils, ESR/CRP
Imaging
Exclude sarcoidosis & atypical pneumonia
Skin biopsy
Histology & direct immunofluorescence if in doubt about diagnosis
