Pathophysiological insights into delayed pressure urticaria: A comprehensive review.

Delayed pressure urticaria (DPU) is a chronic inducible subtype of urticaria, characterized by painful erythematous swelling triggered by sustained mechanical pressure. After pressure stimuli, lesions often appear within 4 to 6 hours, peak around 6 hours later, and persist for 8 hours to 3 days. More than half of patients may have associated symptoms, most often malaise and fatigue. The diagnosis of DPU is based on clinical history and confirmation through provocation testing. Dermographic tester and weighted rod testing are recommended as diagnostic tools by several current guidelines due to their reproducibility and capability to determine individual trigger thresholds. Although the exact pathogenesis remains unclear, mast cell activation, histamine release, eosinophil infiltration, and multiple mediators have been implicated. These mechanisms likely interact synergistically, contributing to the clinical manifestations of DPU. This article reviews the pathogenesis, histopathological findings, effector cells, inflammatory mediators, neuropeptides, adhesion molecules, and unmet clinical needs associated with DPU. A deeper understanding of these complex processes may facilitate the development of more effective targeted immunomodulators and biological therapies for severe and treatment-resistant cases of DPU.