Acquired Acrodermatitis Enteropathica in an Infant
Acrodermatitis enteropathica (AE) is an acquired or inborn (congenital) disorder of zinc metabolism that leads to zinc deficiency. The congenital form typically presents in infants during the first few months of life when they are weaned from breast milk, presenting even earlier in those who are formula fed. Acquired deficiency may be seen at any age. The characteristic clinical features of AE include erythematous, dry, scaly papules and plaques that may evolve into crusted, erosive, pustular lesions. These lesions typically are distributed in an acral and periorificial pattern and are associated with alopecia and diarrhea. Evidence-based recommendations are sparse but generally indicate 3 mg/kg/d of oral zinc supplementation for both congenital and acquired AE. Appropriate dosing helps to avoid acute zinc toxicity involving nausea and vomiting. We report a case of a 3-month-old female infant with acquired AE who was successfully treated with zinc supplementation over the course of 3 weeks.
Practice Points
- Although clinically characterized by the triad of acral and periorificial dermatitis, alopecia, and diarrhea, most cases of acrodermatitis enteropathica (AE) present with only partial features of this syndrome.
- Low levels of zinc-dependent enzymes such as alkaline phosphatase may support the diagnosis of AE.
Management—Treatment of AE includes supplementation with oral elemental zinc; however, there are scant evidence-based recommendations on the exact dose of zinc to be given. Generally, the recommended amount is 3 mg/kg/d.8 For individuals with the congenital form of AE, lifelong zinc supplementation is additionally recommended.9 It is important to recognize this presentation because the patient can develop worsening irritability, severe diarrhea, nail dystrophy, hair loss, immune dysfunction, and numerous ophthalmic disorders if left untreated. Acute zinc toxicity due to excess administration is rare, with symptoms of nausea and vomiting occurring with dosages of 50 to 100 mg/d. Additionally, dosages of up to 70 mg twice weekly have been provided without any toxic effect.10 In our case, 3 mg/kg/d of oral zinc supplementation proved to be effective in resolving the patient’s symptoms of acquired zinc deficiency.
Differential Diagnosis—It is important to note that deficiencies of other nutrients may present as an AE-like eruption called acrodermatitis dysmetabolica (AD). Both diseases may present with the triad of dermatitis, alopecia, and diarrhea; however, AD is associated with inborn errors of metabolism. There have been cases that describe AD in patients with a zinc deficiency in conjunction with a deficiency of branched-chain amino acids.11,12 It is important to consider AD in the differential diagnosis of an AE eruption, especially in the context of a metabolic disorder, as it may affect the treatment plan. One case described the dermatitis of AD as not responding to zinc supplementation alone, while another described improvement after increasing an isoleucine supplementation dose.11,12
Other considerations in the differential diagnoses include AE-like conditions such as biotinidase deficiency, multiple carboxylase deficiency, and essential fatty acid deficiency. An AE-like condition may present with the triad of dermatitis, alopecia, and diarrhea. However, unlike in true AE, zinc and alkaline phosphatase levels tend to be normal in these conditions. Other features seen in AE-like conditions depend on the underlying cause but often include failure to thrive, neurologic defects, ophthalmic abnormalities, and metabolic abnormalities.13
