Clinical profile of pathological urticarial vasculitis: A retrospective study

Abstract Background As there are no definite classification criteria for urticarial vasculitis (UV), its diagnosis is often challenging and usually proposed when urticarial lesions and pathological vasculitis coexist. By analysing the final diagnosis of patients whose skin biopsies showed both urticaria and vasculitis, we sought to decipher the clinical heterogeneity of this condition. Objectives To describe the characteristics of patients with pathological signs of urticaria and vasculitis. Methods We conducted a retrospective, descriptive, single‐centre study within Lille University Hospital and included adult patients with a skin biopsy performed between 2000 and 2021, and whose pathological report mentioned the codes for “leukocytoclastic angiitis” and “urticaria”. Clinical data were then collected from medical records. Results We identified 61 patients with pathological diagnosis of UV and classified them into four groups according to the final diagnosis made by the managing clinicians: 14 patients were diagnosed with UV (normo‐[NUV] or hypocomplementemic UV [HUV]), 10 with urticaria (including 8 chronic urticaria [CU]), 24 with an “undetermined diagnosis” (when elements did not allow firm diagnosis between CU and UV, due to an atypical clinical presentation of urticarial lesions), and 13 with an “other but well‐defined diagnosis”. Fibrinoid necrosis, classically associated with UV, was observed in 4/9 patients (44%) in the urticaria group. Antihistamines were effective not only in all patients with urticaria, but also in NUV and “undetermined diagnosis” group. Conclusions These data suggest that pathological signs of UV may be shared by various clinical situations, raising the hypothesis of a continuous spectrum between CU and UV.