• plaque thickness;
  • psoriasis;
  • systemic medications;
  • topical steroids;
  • UV radiation therapy


Background  The Utah Psoriasis Initiative (UPI) is an expanding database that is being used to identify and characterize phenotypic variants of psoriasis and explore genotype–phenotype relationships. We recently reported distinct morphological variants of psoriasis that are characterized by thickness of lesions (induration) in the untreated state.

Objectives  To explore the clinical relevance of these morphological variants.

Methods  For these analyses, we used the phenotypic data from 282 additional subjects gathered at enrolment into the UPI and compared their phenotype with that of the original 500 patients reported previously. The analysis was further expanded via a longitudinal follow-up of 286 subjects from the original 500 case cohort.

Results  Firstly, the initial findings were confirmed. Expansion of the cohort used for the original observation by about 50% and reanalysis showed that there was no alteration in the proportions of patients expressing thin- and thick-plaque disease phenotypes. Secondly, analysis of the larger cohort showed that this morphological phenotype had clinical relevance: those patients with thin-plaque disease were more likely to report a complete therapeutic response to topical corticosteroids and phototherapy. In contrast, plaque thickness did not appear to be a factor in response to systemic agents.

Conclusions  Using a patient’s baseline plaque morphology to choose a primary treatment modality may result in earlier disease improvement and reduce the cost of therapy.