RESUMEN
BACKGROUND: Psoriasis (Ps) and atopic dermatitis (AD) are chronic systemic immune-mediated diseases that can coexist in an overlapping condition called psoriasis dermatitis (PD). PD patients have intermediate lesions with characteristics of both Ps and AD. PD is very rare in adults but much more frequent in children. Little is known, however, about the course of PD in the pediatric population. The aim of this study was to evaluate the percentage of PD cases in children that evolved to a definite form of Ps or AD and to identify any clinical or epidemiological variables that could predict the course of the disease. METHODS: We performed a prospective multicenter cohort study of children diagnosed with PD between January 2018 and December 2020. We collected participants' clinical and epidemiological characteristics, and pediatric dermatologists determined the percentage of participants who developed Ps or AD. RESULTS: The study included 24 children with PD, with a median age of 7.0 years. After a median follow-up period of 31 months, 83.3% of cases had evolved to a definite form of Ps or AD (44.4% to Ps and 38.9% to AD). Younger age and family history of Ps were associated with progression to AD. Participants who progressed to AD or Ps had a longer follow-up than those with an unchanged PD diagnosis. CONCLUSIONS: Given sufficient time, a large percentage of PD cases in children will evolve into Ps or AD. Long-term clinical follow-up is necessary for a correct diagnosis.