BH16 Early-onset onychodysplasia with multisystem ectodermal features in a toddler: a diagnostic challenge

Abstract

Early-onset nail dystrophy is uncommon and may be misinterpreted as inflammatory nail disease. Nail involvement is recognized in paediatric psoriasis and may present with thickening, onycholysis and paronychia. Psoriasis presenting in infancy is rare, and nail changes in children aged < 2 years have been described only in a small historical case series. Ectodermal dysplasias are inherited disorders affecting multiple ectoderm-­derived structures, including nails, teeth and hair. When nail dystrophy presents alongside extracutaneous abnormalities in early childhood, distinguishing isolated inflammatory nail disease from syndromic ectodermal pathology is important. A girl aged 2 years and 1 month was first referred at 18 months with chronic paronychia and dystrophy affecting all 20 nails. The nail changes were only partially responsive to topical therapy. Initial differential diagnoses included early-onset nail psoriasis and infection; however, the atypical age of onset and dysmorphic features raised suspicion of a unifying genetic diagnosis. Additional clinical features included abnormal dentition consistent with amelogenesis imperfecta, dysmorphic facial features (including telecanthus and hypertelorism), scalp and palmar eczema, and persistent bilateral epiphora. Ophthalmological assessment identified astigmatism, low myopia and abnormal eyelid anatomy, with concern for lacrimal system involvement. Developmental milestones were otherwise normal. There was a maternal history of guttate psoriasis; no other family members were affected. Genetic investigations to date, including karyotype and chromosomal microarray, were normal. Nail unit biopsy from two digits demonstrated abnormal nailbed architecture with thickened fragmented keratin, acanthotic epidermis, increased vascularity and mild chronic inflammation, consistent with onychodysplasia. No fungal elements or malignancy were identified. Given the involvement of multiple ectodermal structures, further genetic testing was recommended in accordance with the NHS England National Genomic Test Directory for ectodermal dysplasia (R163). This case highlights a rare presentation of early-onset onychodysplasia with multisystem ectodermal involvement, initially mimicking nail psoriasis, and underscores the importance of multidisciplinary evaluation in achieving diagnostic clarity and avoiding misclassification.