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Snapshot diagnosis - what's this blistering rash on a newborn?

Dr Mike Wyndham describes how he discovered what was causing fluid-filled blisters in the groin of a two-week-old child

Dr Mike Wyndham describes how he discovered what was causing fluid-filled blisters in the groin of a two-week-old child

The patient

Just two weeks old and already making his first visit to the GP. The boy's rash had been present for a couple of days in the groin and suprapubic area but it was now spreading out to his thighs and – alarmingly – was starting to blister.

It was not responding to treatment with a barrier cream. There had been no problems with the pregnancy and there was no family history of skin disease.

First instinct

The commonest infection I usually encounter in the nappy area and surrounds is candida – frequently in association with nappy dermatitis. This baby certainly didn't have this.

The blisters seriously bothered me as the primary bullous eruptions, pemphigus, pemphigoid and dermatitis herpetiformis, are certainly not associated with infants.

Pemphigus and pemphigoid usually occurs in older adults. Bullous pemphigoid may occur in a child under six years old but I have never seen it.

Dermatitis herpetiformis, when it occurs in children, is usually between the ages of six and 11 years.

Differential diagnosis

• Epidermolysis bullosa simplex

• Dermolytic bullous dermatosis

• Bullous impetigo

The hidden clue

A bulla is defined as a fluid-filled lesion bigger than 1cm in size. The blisters were less than 1cm and this made a true bullous disorder less likely.

Getting on the right track

Attention to detail is a must. I took a close look at the blisters and saw what looked like pus in them.

This suggested infection, and therefore bullous impetigo was the likely diagnosis. Although I initially treated the baby with oral flucloxacillin and topical fusidic acid cream, the infection advanced and I arranged for hospital admission for intravenous antibiotics.

Impetigo may be caused by either staphylococcal or streptococcal infection with the former being the most common cause. When blisters are present, then Staphylococcus aureus is the usual cause.

Dr Mike Wyndham is a GP in Edgware, north London

Blistering rash

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