(a) Vertical growth and radial expansion models emerged from contrasting epidermal thickness and PASI between Asian small, Asian intermediate, and Western large psoriasis. (b) In the model of vertical growth phase, epidermal thickness was correlated with the numbers of CD3+ T cells and CD11c+ dendritic cells within the epidermis and dermal papillae (method of counting cells in epidermis and dermal papillae: Supplementary Figure S6 online). (c) In the model of radial expansion phase, PASI was correlated with CD3+ T cells and CD11c+ dendritic cells in total psoriasis body surface area (d) Summary of exploratory models (r = Pearson correlation, p < 0.0001, PASI: Psoriasis Area and Severity Index, Number of inflammatory cells in total psoriasis body surface area = cell count in the slide section × body surface area × proportion of psoriasis involvement).