Psoriasis dermatitis: a new entity or a different phenotypic expression of psoriasis and atopic dermatitis?

Background: Psoriasis (P) and atopic dermatitis (AD) share some common characteristics. The resulting clinical picture with shared manifestations is a new entity called psoriasis dermatitis (PD), atopic psoriasis or psorema. The purpose of this study was to identify the clinical manifestations of this new dermatological condition, focusing on the adult population.

Methods: We recruited adult patients from two outpatient clinics, the "severe psoriasis" and the "adult atopic dermatitis," between January 1, 2021, and December 31, 2021. The 26 patients meeting the inclusion criteria were followed for 12 months, and two control groups of patients were enrolled in the same period.

Results: The frequencies of the variables examined within the patients affected by PD were compared with those of P or AD group. The age at disease onset was significantly higher in PD patients and the duration of symptoms was also significantly lower in PD patients, compared to both P and AD groups. Affected areas were similar between PD and P, instead the scalp, feet and genitals were more frequently involved in the PD group than in the AD group.

Conclusions: P and AD seem part of a spectrum rather than a dichotomy, where PD is an entity in the middle of this spectrum.