A comparative study of childhood psoriasis and atopic dermatitis and greater understanding of the overlapping condition, psoriasis-dermatitis.

Psoriasis (Pso) in children may be confused clinically with atopic dermatitis (AD) and, indeed, the two conditions may co-exist. The aim of this study was to determine historical and clinical features that are different in paediatric Pso and AD and to describe children who have features of both: psoriasis-dermatitis overlap (PD). Children with features of psoriasis or eczema, or both, who were referred to paediatric outpatients and/or private rooms were evaluated. Data were collected from 170 consecutive children aged less than 12 years between July 2011 and November 2011. Participants were classified by described criteria as having Pso (n = 64), AD (n = 62) or PD (n = 44). Only 9.4% of children with Pso were correctly diagnosed by the referring doctor. Children with Pso relative to AD were more likely to have had a history of scaly scalp and nappy rash in infancy, a family history of psoriasis, current scalp and periauricular rashes, defined, patchy plaque morphology and papulosquamous rashes not typical of adult psoriasis on extensor elbows and knees. Children with PD had features of both but presented most often as typical paediatric psoriasis combined with flexural eczema. Children with Pso and PD responded well to specific treatment strategies for psoriasis, including potent topical corticosteroids (TCS), calcipotriol and phototherapy. Both Pso and PD tended to require more potent TCS than AD to achieve disease suppression. We found that Pso and PD in children both differ clinically from AD and have identified historical and clinical features that characterise childhood Pso.