Pityriasis rubra pilaris exacerbation with topical use of imiquimod.

The role of immune response modifiers is increasing in the treatment of dermatologic diseases. Imiquimod, a toll-like receptor agonist, results in up-regulation of proinflammatory cytokines for improved immune surveillance. Although topical use is generally well-tolerated, imiquimod can potentially result in systemic effects and exacerbate generalized inflammatory papulosquamous diseases of the skin. We report the case of a 67-year-old man who was treated with imiquimod for actinic keratosis and developed fever and a progressive erythematous papulosquamous eruption that was histologically consistent with pityriasis rubra pilaris.