Paediatrics: Vesiculobullous rashes

Vesiculobullous rashes

Erythema multiforme

Cause

Immunologically mediated syndrome. May be idiopathic, but usually pre-cipitated by infection (e.g. mycoplasma, herpes simplex, other viruses) or drugs (e.g. sulfonamides, penicillin).

Presentation

See b Plate 4.

•   Crops of characteristic symmetric ‘target’ lesions develop with pallid or purple centre surrounded by erythematous ring.

•   May also be haemorrhagic, red macules or large bullae.

•   Lesions last 2–3wks and affect hands, feet, elbows, knees.

•   Typically, mucous membrane ulcers occur (buccal, eye, genitalia).

Treatment

If precipitating infection recurs treat early as tends to cause rash again, e.g.

topical aciclovir for recurrent HSV.

•   Fluid maintenance.

•   Analgesic mouthwashes.

•   Lip emollient ointment.

•   Oral antihistamines.

Prognosis 

Complete recovery, but may recur.

Stevens–Johnson syndrome/toxic epidermal necrolysis

Severe, and overlapping condition with erythema multiforme except usu-ally drug induced with viral infection rarely implicated.

Presentation

See b Plate 5.

•   Widespread blisters/bullae over erythematous, purple macular, or haemorrhagic skin.

•   Mucous membranes often affected with haemorrhagic crusting.

•   Rubbing may cause skin separation at epidermodermal junction (= positive Nikolsky sign).

•   Also possible fever, arthralgia, myalgia, prostration, renal failure, pneumonitis, conjunctivitis, corneal ulceration, blindness.

Treatment

•   Supportive, as for severe burns (e.g. hydration, airway protection).

•   Identify causative antigen and remove/treat.

•   Frequent emollient ointment.

•   Specialist eye care.

•   Systemic corticosteroids or immunoglobulin used in first 2–3 days may be helpful if life-threatening.

Prognosis 

Can be life-threatening. Recovery usually occurs in 3–4wks.

Staphylococcal scalded skin syndrome

Exotoxin-mediated epidermolysis s to Staphylococcus aureus infection (which may be trivial). Occurs in children <5yrs.

Presentation

• Extensive tender erythema with flaccid superficial blisters/bullae (‘scalded appearance’).

• Erosions and +ve Nikolsky sign.

• Crusting around eyes and mouth, fever.

Treatment

• Supportive treatment and analgesia.

• IV anti-staphylococcal antibiotics.

• Gentle skin care, emollient ointments.

Prognosis 

Rapid recovery without scarring.

Impetigo

Highly contagious Staphylococcus aureus or B-haemolytic streptococcal superficial skin infection. May be p or complicate other skin disease (e.g. HSV infection, eczema, scabies). Risk factors include overcrowding and poor hygiene.

Presentation

• Superficial, rapidly spreading initially clear blisters that rapidly develop into straw-coloured ‘dirty’ looking lesions with yellow crusting.

• Often starts around nose and face; neonates may develop bullous impetigo.

• Risk of staphylococcal scalded skin syndrome or acute glomerulonephritis (streptococcal).

Investigation 

Skin swabs for bacterial culture and sensitivity.

Treatment

Rapidly resolves if:

• bathe crusts off using antiseptics (contain infectious bacteria);

• antibiotics (e.g. topical mupirocin 2% ointment or oral flucloxacillin);

• treat any predisposing condition.

Eczema herpeticum Traumatic blisters

Caused by friction, burns, or insect bites. Sterile aspiration of blister within 12hr after appearance, and pressure dressing may be curative.

Epidermolysis bullosa