Table Of Contents
Erythema Multiforme
This is a common reaction pattern of blood vessels in the dermis with secondary epidermal changes. It is an acute, self-limited Type IV hypersensitivity reaction. It manifests clinically as characteristic erythematous iris-shaped papular and vesiculo-bullous lesions (Bullseye). The age of onset is around 20 years for 50% of patients. Males are more commonly affected than females. It can be either minor or major. The diagnosis is mainly clinical. Prognosis is good, but with herpes simplex, it is a recurrent disease.
Erythema multiforme major vs. minor
| Major | Minor | |
|---|---|---|
| Lesion | Has extensive target lesions acral and central body and is potentially life-threatening | Target lesions are localised and few |
| Site | Two or more sites of mucosal inflammation | Only one mucous membrane has mucositis |
- Causes
- Infection: Herpes simplex (most common cause), Mycoplasma pneumoniae
- Drugs: Sulfonamides, phenytoin, barbiturates, phenylbutazone, penicillin, or allopurinol
- Idiopathic
- Signs and symptoms
- The evolution of lesions occurs over several days
- May have a history of prior erythema multiforme
- May be pruritic or painful, particularly mouth lesions.
- In severe forms constitutional symptoms such as fever, weakness, and malaise are present
- Mucous membrane involvement causes painful ulcers in the oral (most common), genital, and ocular mucosa.
- Characteristics of the skin lesions:
- Lesions may develop over ≥ 10 days. Macule → papule (1 to 2 cm) → vesicles and bullae in the centre of the papule.
- Dull red. Iris or target-like lesions result and are typical and localized to hands and face or generalized
- Bilateral and often symmetric. Affects the back of hands and feet first.
- Treatment
- Prevention: Control of herpes simplex using oral acyclovir, valaciclovir or famciclovir may prevent recurrence
- Glucocorticoids: In severely ill patients, systemic glucocorticoids are usually given (prednisone, 0.5mg to 1mg per kg/ day in divided doses, tapered in 7 days, but their effectiveness has not been established by controlled studies)
- Conservative management of mucositis: saline washes, topical antibiotics for erosions on skin, pain control, assisted feeding in severe cases, managing stress stomach ulcers due to mucositis
- In severe cases (EM major), admit and treat as thermal burns
