AN INFANT WITH BLISTERS
History
Amy is an 8-day-old infant referred to the paediatric day unit by the midwife. In the past 24 hours she has developed several blisters in the nappy area plus a few on her trunk and arms. Amy was born at 38 weeks’ gestation, following an uneventful pregnancy, to healthy, unrelated parents. There were no risk factors for infection (e.g. prolonged rupture of membranes). She is their first baby. Her mother has quite severe eczema and asthma. Amy is breast-feeding well and has regained her birth weight.
Examination
Amy looks generally well. Her temperature is 36.8C. There are no dysmorphic features. Her pulse is 130 beats/min and her capillary refill time 2 s. Scattered over her skin (see Fig. 47.1) in the described distribution she has several flaccid, transparent, cloudy, fluid-filled bullae of varying size from 2 to 15 mm in diameter. One or two have ruptured, leaving a shallow, moist erosion.
Figure 47.1 Amy’s skin.
Amy also has a 5-mm-diameter soft glistening pink lesion within the umbilicus where the cord has dropped off. It bleeds a little on contact and there is a small blood stain on her nappy. Examination of the cardiovascular, respiratory and abdominal systems is unremarkable. Her anterior fontanelle is soft. She handles well and has normal tone and primitive reflexes.
INVESTIGATIONS
Normal
Haemoglobin 14.6 g/dL 13–21 g/dL
WCC 13.3 109/L 6–22 109/L
Platelets 235 109/L 150–400 109/L
Sodium 138 mmol/L 134–146 mmol/L
Potassium 4.4 mmol/L 3.0–7.0 mmol/L
Urea 2.2 mmol/L 1.8–6.4 mmol/L
Creatinine 46 µmol/L 27–62 µmol/L
CRP 6 mg/L 6 mg/L
Questions
• What is the most likely cause of the bullae?
• What is the management?
• What is the umbilical lesion likely to be, and how would you treat it?
Medicine
These flaccid, fragile blisters are characteristic of bullous impetigo. This is the localized presentation of the staphylococcal scalded-skin syndrome and patients are otherwise well. At the other end of the spectrum are those who present with generalized cutaneous involvement and systemic illness. Both are caused by Staphylococcus aureus, most of which are from phage group 2. In bullous impetigo the organism can be cultured from the lesions but the systemic form is mediated by exfoliative toxins and swabs are sterile. The common weepy, golden, crusty forms of impetigo start on skin that has been damaged, e.g. by insect bites, chickenpox or abrasions. It spreads easily to other sites and to other children. The causative organism is also usually Staphylococcus aureus but generally not from phage group 2. Group A β-haemolytic Streptococcus can also cause impetigo. Patients with eczema are at increased risk of infective exacerbations due to these organisms. It is likely that this baby’s infection was transmitted from her mother, either because of her eczema or because she has mastitis. A much rarer cause of blistering in the neonatal period is epidermolysis bullosa. There are several different types that differ in severity, clinical features, distribution and inheritance patterns, but all are characterized by blisters that develop with trauma and are exacerbated in warm weather. Blisters present at birth would be strongly supportive of this diagnosis. Treatment is with a β-lactamase-resistant antibiotic such as co-amoxiclav. This infant is well and so the oral route can be safely used whilst monitoring for a satisfactory response. In systemic scalded skin syndrome, antibiotics are administered parenterally. Such patients need careful monitoring because they are at risk of significant heat and fluid losses. They also require adequate pain relief. The umbilical lesion is likely to be a granuloma. The umbilical cord usually dries and separates within 6–8 days after birth and the surface epithelializes. Where this is incomplete or there is mild infection, granulation tissue can develop and persist. A granuloma is not painful. A number of treatments are available, including cauterization using a silver nitrate stick. This can be repeated once a week until the lesion has resolved. It is crucial to differentiate the common umbilical granuloma from the rare umbilical polyp which results from persistence of the omphalomesenteric duct or the urachus. If it communicates with the ileum or bladder, there may a faeculant or urinary discharge. Treatment is surgical.
KEY POINTS
• Skin infections due to Staphyococcus aureus have a range of presentations from mild, localized lesions to severe, systemic infections.
• Blistering present at birth is likely to be due to epidermolysis bullosa.
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