Atypical acute urticaria in children and its relationship with urticarial vasculitis

Aim: In childhood, urticarial lesions are sometimes associated with purpura. This form might be identified as atypical, and may also be related to urticarial vasculitis (UV). The aim of this study was to assess the clinicopathologic characteristics of UV in children with atypical urticaria.Materials and methods: Fifteen children with atypical urticaria were evaluated with medical history, physical examination,and laboratory and skin punch biopsy findings.Results: Infections were detected as possible precipitating factor in 12 patients. Complement levels were normal in all. On histological examination, 6 patients (40%) had neutrophil-predominant infiltrate and 9 (60%) patients had lymphocyte-predominant infiltrate. All the patients with a neutrophil-predominant infiltrate showed leukocytoclastic vasculitis (LCV).None of the 9 patients with perivascular infiltrate of lymphocytes showed LCV. Eosinophil infiltration was present in 8 patients. On direct immunofluorescence examination, 5 of the 6 patients with LCV had deposits of immunoreactants,mainly of Ig G, Ig M, and fibrinogen.Conclusion: Our findings, in contrast to the literature, suggest that UV is i) not rare in children, ii) generally triggered by infection, iii) normocomplementemic, and iv) self-limited. The biopsy specimens may show neutrophil-predominant infiltrate with LCV or lymphocyte-predominant infiltrate without LCV. These results imply that in children with normocomplementemic UV it may not be necessary to perform a skin biopsy.