What is Delayed Pressure Urticaria?
Delayed pressure urticaria (DPU) is a physical urticaria characterized by the development of deep, painful or tender swellings that occur 3-12 hours after sustained pressure application to the skin, with lesions persisting for up to 48 hours. 1, 2, 3
Clinical Presentation
DPU presents with distinctive features that differentiate it from other urticarias:
- Delayed onset: Wheals develop 30 minutes to 24 hours after pressure stimulus, most typically 3-12 hours post-exposure 1, 2, 4
- Prolonged duration: Unlike ordinary urticaria (2-24 hours) or other physical urticarias (<1 hour), DPU lesions take 2-6 hours to develop and may persist up to 48 hours before fading 1
- Deep swellings: Lesions present as deep, edematous swellings rather than superficial wheals 3
- Pain and tenderness: Characteristically itchy, tender, or painful—distinguishing DPU from typical pruritic-only urticaria 2
Common Sites of Involvement
Lesions develop at pressure-bearing areas:
Pathophysiology
The mechanism involves mast cell activation through non-immunologic pathways, with multiple mediators beyond histamine, including proinflammatory cytokines. 3 This explains why H1-antihistamines alone often provide less satisfactory results compared to their efficacy in other urticarias 3, 5.
Diagnostic Confirmation
- Dermographometer challenge test: Sustained pressure application (typically 70 seconds) confirms diagnosis when characteristic delayed wheals develop 2
- Pressure provocation test: Evaluates response to treatment by assessing wheal formation after controlled pressure application 6
Clinical Context
DPU frequently coexists with chronic spontaneous urticaria, complicating both diagnosis and management. 3 Prevention is difficult because pressure exposure is often unavoidable in daily activities 3.