Zinc-responsive Acral Hyperkeratosis as a Sequele of Acrodermatitis Enteropathica

Dear Editor, Zinc-responsive acral hyperkeratosis (ZRAH) is a rare dermatological condition, characterized by persistent hyperkeratotic lesions on acral sites that do not respond to conventional therapies. We present the case of a boy with a history of inadequately treated acrodermatitis enteropathica (AE) developing bilaterally symmetrical acral hyperkeratotic lesions suggestive of ZRAH. A 6-year-old boy was brought to dermatology outpatient care with hyperkeratotic acral lesions for 8 months, unresponsive to prior treatments. Clinical examination revealed asymptomatic, bilaterally symmetrical hyperpigmented hyperkeratotic plaques over the bony prominences of the feet, accompanied by fine scales [Figure 1a]. Dermoscopy exhibited brown globules and white areas resembling a “cracked-pavement appearance” [Figure 1b]. The patient’s hair appeared yellowish-brown, coarse, and brittle [Figure 2a], with dermoscopy revealing golden-brown translucent hairs interspersed among normal black hairs [Figure 2b]. Nail examination indicated transverse ridges and lamellar splitting.Figure 1: (a) Bilaterally symmetrical hyperpigmented hyperkeratotic smooth surfaced well defined plaques over dorsum of foot; (b) Brown globules (black arrow) and structureless white areas (yellow circle) surrounded by lines of white scales giving a “cracked-pavement appearance”Figure 2: (a) Yellow arrow is showing golden part of the hair, Legend for (b) golden-brown translucent hair in between normal looking black hair with fine greasy scales and single hair showing alternate golden (yellow arrow) and black bandsThe patient had a previous history of oral and perioral ulcers. At 6 months of age, he experienced diarrhea, perianal lesions, and diffuse scalp alopecia, which resolved over 5 years but left hyperpigmented patches on the buttocks. Zinc supplementation was initiated but discontinued after 1 year. He was born full-term and breastfed adequately. Investigations revealed normal zinc levels (92 µg/dL), complete blood counts, alkaline phosphatase, serum albumin, and iron studies. Viral serology, including hepatitis C, was negative. A provisional diagnosis of ZRAH was made based on the clinical findings. The patient was started on oral zinc sulfate (50 mg/day) and a zinc-rich diet. Significant improvement was observed within 6 weeks, and after 6 months, skin and hair showed marked recovery [Figure 3a and b].Figure 3: (a) Resolution of acral lesions after 6 months of treatment; (b) Improvement in hair density and appearanceZRAH is an uncommon condition, typically linked to chronic renal failure and diabetes mellitus in adults but may also arise from untreated zinc deficiency, notably in cases such as AE. AE, an autosomal recessive form of zinc deficiency, presents with a triad of periorificio-acral dermatitis, alopecia, and diarrhea, with low or normal serum zinc levels. Zinc plays a crucial role in melanocyte proliferation and keratinization, and its deficiency can cause light-colored hair, telogen effluvium, and structural abnormalities of hair shaft.[1,2] Nail manifestations include Muehrcke’s lines, Beau’s lines, brittle nails, and onychoschizia that have also been described in association with AE.[3] In this case, the patient’s history suggested inadequately managed AE leading to acral hyperkeratotic lesions. Chronic zinc deficiency may disrupt keratinocyte turnover in pressure-prone areas, resulting in lichenified plaques.[4] Even after zinc levels normalize, some patients develop persistent hyperkeratotic patches, likely due to the long-term effects on skin integrity. Few pediatric cases reported showed association with nephrotic syndrome and disseminated tuberculosis.[5] Differential diagnoses included lichen simplex chronicus, psoriasis, and necrolytic acral erythema. Acquired zinc deficiency was ruled out based on the typical triad history and normal zinc levels. Clinical improvement with zinc supplementation confirmed ZRAH as the primary diagnosis. ZRAH has been primarily reported in adults with systemic associations, with limited pediatric cases. This case suggests ZRAH could be a sequela of an inadequately treated AE. Further studies are needed to establish this correlation. Recognizing ZRAH is crucial for dermatologists, as it mimics other hyperkeratotic conditions but requires specific treatment. Declaration of consent The authors certify that they have obtained all appropriate consent forms, duly signed by the parent (s)/guardian (s) of the patient. In the form, the parent (s)/guardian (s) has/have given his/her/their consent for the images and other clinical information of their child to be reported in the journal. The parents understand that the names and initials of their child/children will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.