Case 4

A 4‐month‐old baby boy was referred to the dermatology department with a 5‐week history of a blistering rash on the face and in the nappy area. He also had mild diarrhoea. Treatment of the rash with topical steroids and oral antibiotics had been of no benefit. He had been born prematurely at 28 weeks' gestation by emergency Caesarean section for preterm labour, unstable lie and past maternal history of a neonatal death. His birth weight was 1460 g. His neonatal course was complicated by surfactant deficient lung disease, jaundice, an atrial septal defect, a patent ductus arteriosus which was treated with indomethacin and anaemia of prematurity for which he was twice transfused. He had a family history of atopy with his mother having eczema and his sister having asthma. He had been fully breast fed since birth. On examination he was irritable and had a low grade fever. Bilateral conjunctivitis was noted. He had a marginated erythematous eruption on the cheeks, chin and neck which was composed of multiple and confluent maculopapular lesions and associated with blistering, desquamation and crusting (Fig. 1). The perineum was similarly affected. Investigations revealed normal serum electrolytes and cultures from skin swabs grew Staphlococcus aureus and Coliforms. A 4‐month‐old baby boy with a marked facial eruption composed of multiple and confluent maculopapular lesions and blisters. What is your diagnosis? Transient symptomatic zinc deficiency in a breast‐fed premature infant: an acrodermatitis enteropathica‐like eruption. Zinc deficiency was confirmed with a serum zinc level of 5.7 µmol/L (normal 10–20 µmol/L). He was started on oral zinc supplements, oral antibiotics on the basis of culture sensitivities, emollients and topical miconazole nitrate 2%, hydrocortisone 1% (daktacort). Clinical improvement occurred within 7 days and complete skin healing was achieved within 3 weeks (Fig. 2). He remained on oral zinc supplements for 7 months until well established on a normal diet. There has been no recurrence of the rash. Complete resolution after oral zinc. The clinical features of transient symptomatic zinc deficiency are indistinguishable from acrodermatitis enteropathica and include an erythematous vesiculobullous eruption in a perioral, perineal and acral distribution, loose stools, alopecia, fever, conjunctivitis and behavioural changes such as irritability and withdrawal with lack of spontaneous smiling.1 Acrodermatitis enteropathica is an autosomal recessive disorder of zinc absorption which typically presents at weaning and thereafter requires life‐long zinc replacement. In infancy maternal breast milk has both a protective and therapeutic effect.2 In contrast, however, the presentation of transient symptomatic zinc deficiency is usually between 8 and 24 weeks of age and has been documented to occur in infants who are exclusively breast fed. In most reported cases this was due to inadequate maternal breast milk zinc despite normal serum zinc levels.3 Moreover, following zinc supplementation a rise in serum but not breast milk zinc level was detected in these women. This led to suggestions that breast milk zinc could be low because of defective mammary zinc secretion. A genetic basis for this is strongly supported by a report of 10 infants from 3 interrelated families who developed symptoms whilst breast fed zinc‐deficient milk.4 A genetic defect in mammary zinc secretion has been described in female mice homozygous for a mutant gene lethal milk (lm).5 However, there have been reports in the literature of symptomatic zinc deficiency in preterm infants fed maternal milk with normal zinc content. With prematurity the situation is more complex as these infants are particularly susceptible to acquired zinc deficiency for several additional reasons. The greatest accumulation of zinc occurs in the third trimester; hence total body zinc is inversely proportional to the degree of prematurity. Also, preterm infants are prone to a negative zinc balance for up to 60 days, secondary to poor zinc absorption, increased zinc secretion by the intestine and increased zinc demand because of rapid growth and development.6 In transient symptomatic zinc deficiency the effects of zinc replacement are prompt. It takes only 3 days to 2 weeks for the clearing of the skin lesions. The duration of treatment is transient and is only necessary until weaning. Our patient maintained normal serum zinc levels and thrived after zinc supplementation was discontinued.