Abstract: 【Abstract】 Objective To compare and analyze the similarities and differences in clinical manifestations, laboratory findings, pathological characteristics, and prognosis between urticarial vasculitis （UV） and chronic spontaneous urticaria with pigmentation （CSUwp）. Methods A retrospective analysis was conducted on the clinical data and follow-up results from 35 UV patients and 54 CSUwp patients who attended the Department of Dermatology, Southwest Hospital, Army Medical University from 2014 to 2024. The clinical characteristics （duration of rash, pigmentation, petechiae and ecchymosis, itching, burning sensation, fever, fatigue, skin lesion characteristics, etc.）, laboratory test results, pathological features, and prognosis were compared between the two groups. Statistical analysis was carried out by t test, chi-square test, Mann-Whitney U test, and Kaplan-Meier survival analysis. Results There were no significant differences in gender, age, or age of onset between the UV group and CSUwp group （all P < 0.05）. The proportions of patients with petechiae/purpura （68.57% ［24/35］ vs. 11.11% ［6/54］）, and those with burning sensation （22.86% ［8/35］ vs. 3.70% ［2/54］） were significantly higher in the UV group than in the CSUwp group （both P < 0.05）. Compared with the CSUwp patients, the UV patients presented with a greater number of lesions, larger lesion areas, and more frequent involvement of the lower limbs （all P < 0.05）,also showed significantly higher incidence rates of peripheral blood complement reduction, perivascular neutrophil infiltration, nuclear dust, fibrinoid necrosis of the vessel wall, and erythrocyte extravasation （all P < 0.05）, as well as more extensive dermal perivascular inflammation （Z = -4.506, P < 0.001）. Among patients who achieved remission, the natural disease course was significantly longer in the CSUwp patients than in the UV patients （6.00 ［2.5, 24］ months vs. 2.00 ［0.5, 24］ months; Z = -2.618, P = 0.009］. However, the survival analysis showed no significant difference in the natural disease course or clinical outcomes between the two groups （χ2 = 2.771, P = 0.096）. There were also no significant differences in rash duration or in the incidence rates of itching, angioedema, or joint pain between the two groups （all P > 0.05）. Conclusions UV patients exhibited certain differences from CSUwp patients in clinical characteristics, laboratory test results, histopathological features, and prognosis. However, whether their natural disease courses differ requires further follow-up studies to confirm.

Key words: Urticaria, Urticarial vasculitis, Chronic spontaneous urticaria, Skin manifestations, Pathologic processes, Therapy, Prognosis