An acute monomorphic eruption in a systemically unwell atopic child


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AN ACUTE MONOMORPHIC ERUPTION IN A SYSTEMICALLY UNWELL ATOPIC CHILD

History
A 6-year-old boy is brought to the accident and emergency department by his parents
with a 5-day history of worsening eczema associated with malaise and lethargy. In addition
to worsening pruritus and sleeplessness he complains of painful skin, particularly
around his face, neck, chest and forearms. He quantifies the level of pain as 8 out of 10.
His current flare is not responding to diligent application of his usual eczema treatments
according to his ‘step-up’ management plan.
The onset of his eczema was at the age of 4 months, and although moderately severe
in infancy it has been reasonably controlled since starting primary school, with regular
use of emollients and mild to moderately potent topical steroids. His background history
includes egg allergy (now partially outgrown in that he tolerates well cooked egg in
cakes) and asthma, currently stable. He has never been admitted to hospital before. He
is fully vaccinated to date and had chickenpox at the age of 4 years. His father suffers
from hay-fever and experienced childhood eczema and asthma. He has one older sister
(aged 14) who is well.
His medication includes:
• Regular emollients both as leave-on preparations and soap substitute
• Topical tacrolimus 0.1% twice daily applied to affected areas for the management of
flares
• Hydroxyzine 10 mg nocte during flares and salbutamol inhaler on a prn basis
Examination
He looks unwell and is febrile at 38.5 °C. Systemic examination is normal except for
widespread lymphadenopathy. There is no evidence of conjunctival erythema and his
vision is normal. He has generalized moderate to severe eczema with erythema, dryness,
excoriation and lichenification. He has a superimposed monomorphic eruption over his
lower face, chest and forearms. The eruption is composed of multiple 23-mm monomorphic
‘punched-out’ erythematous lesions in various stages of evolution (Fig. 3.1). Some of
the lesions are vesicular, others pustular, some coalescing, most are eroded and covered
with a golden exudate and others haemorrhagic crust

What are these lesions?
• How would you confirm the diagnosis?
• What complications can be associated
with them?
• What is their management?

These are typical lesions of herpes simplex virus (HSV) infection complicating atopic
eczema. This eruption is called eczema herpeticum, or less commonly Kaposi’s varicelliform
eruption.
Diagnosis can be confirmed by viral swab of a blister or eroded area. Many tests can
detect HSV within tissue or blister fluid. HSV can be inferred by positive staining or
electron microscopy or specifically identified as types HSV-1 or HSV-2 by immunofluorescence,
culture, or polymerase chain reaction. Bacteriology swab for microscopy and
culture should also be undertaken.
Significant morbidity is associated with eczema herpeticum. The main potential complications
include superimposed bacterial infection (Staphylococcus or Streptococcus)
with risk of systemic sepsis, ocular involvement (in particular, HSV keratitis) and, rarely,
systemic HSV infection with risk of spread to the liver, the lungs, the brain, the gastrointestinal
tract and even the adrenal glands. In addition pain and discomfort associated
with eczema herpeticum is significant.
The management of widespread eczema herpeticum includes systemic treatment of HSV
infection with aciclovir, identification and treatment of any superimposed bacterial
infection or strategies to prevent superimposed infection, such as antibacterial washes
and creams. Topical tacrolimus should be discontinued in this patient as this may exacerbate
the cutaneous spread of HSV. These cases are usually managed as in-patients,
initially with intravenous aciclovir – as oral preparations can be poorly absorbed.
Ophthamological review should be sought in cases of diffuse facial herpes simplex infection
or where conjunctival/corneal involvement is suspected.
In a minority of cases recurrences can occur. Rapid treatment of incipient lesions with
topical aciclovir may help prevent disseminated eczema herpeticum.