1 Pressure Challenge Test and Histopathological Inspections for 17 Japanese cases with Clinically Diagnosed Delayed Pressure

Delayed pressure urticaria (DPU) is characterized by deep dermal wheals that appear in response to a local continuous pressure. Although it has been reported to complicate as many as 40% of cases of Caucasian patients with chronic urticaria, no definitive cases of Asian/Japanese patients have been reported in English literature. Here, we identified 17 cases of DPU, among 540 Japanese patients with urticaria (3.1%), based on careful history taking, pressure challenge test and, ideally, skin biopsy. Twelve out of 17 patients (70.5%) who undertook pressure challenge testing, developed wheal and erythema in the area of pressure 1-12 hours later. Six out of 15 patients (40%) were positive for the autologous serum skin test (ASST). All cases were complicated with ordinary chronic urticaria, and all specimens of skin biopsies performed for 12 patients showed substantial eosinophil infiltration. All cases were resistant to antihistamines with or without other non-steroidal medications and eventually treated with 0.25-1.5 mg/day of betamethasone. However, 12 of them (70.6%) were able to cease steroid use because of cure or remission. For those cured or in remission, the duration of steroid administration and that from the onset to diagnosis was 11.2 ± 11.0 and 54.8 ± 60.2 months (mean ± SD), respectively. DPU may be identified as a relatively rare complication of Japanese patients with chronic idiopathic 3 urticaria. A proper diagnosis and a small amount of steroid may be beneficial for the treatment of DPU.