A 17-month-old girl with a history of phenylketonuria (PKU)and chronic kidney disease (CKD) secondary to unilateralrenal agenesis presented with failure to thrive, diarrhea,and an extensive skin rash. Her parents reported increasedirritability, decreased oral intake, and a gradually worseningrash over the last 14 days, with watery diarrheapresent for 3 days. The patient was on a special amino-acidrestricteddiet formula since birth for PKU and CKD. Onexamination, a diffuse erythematous confluent rash waspresent in the perioral region and the inguinal and perianalareas (as shown in Figs. 1 and 2). Her phenylalanine, tyrosine,and branched-chain amino acid contents were verylow on the amino acid quantitative panel. Zinc levels andkidney function tests were normal. The patient’s conditionwas clinically diagnosed as acrodermatitis dysmetabolica,which was confirmed by a skin biopsy. Skin findings such asacrodermatitis enteropathica are common in patients withaminoacidopathies, including PKU, and are also found insubjects with organic acidemias, urea cycle disorders, andessential fatty acid deficiency.1 However, unlike acrodermatitisenteropathica, the rash in acrodermatitis dysmetabolicausually does not respond to zincsupplementation. The etiology of the rash is secondary toessential amino acid deficiency, leading to keratinocytegrowth arrest.2 The treatment involves timely supplementationof the amino acids that are deficient. Frequentmonitoring of amino acid levels and avoidance of aminoacid imbalance are key factors in the prevention of this skincondition. The patient was started on a special diet withsufficient amino acids, and her rash gradually improvedwith dietary adjustments and emollients.
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