The dysfunctionality of the protective skin barrier in psoriasis allows easier cutaneous penetration of various contact haptens; thus, such patients can develop allergic contact hypersensitivity as a comorbidity. Both skin conditions involve T-cell-mediated mechanisms. Dermatologists and allergists should consider assessing allergic contact cell-mediated hypersensitivity in selected psoriasis patients, especially those with palmoplantar psoriasis and who are refractory to topical treatments, and in patients with psoriasis, with or without arthritis, treated with biologics that present skin lesions clinically suggestive of contact dermatitis.
