The classic histopathological findings of urticaria include dermal edema and a sparse perivascular infiltrate of neutrophils, eosinophils, macrophages, and lymphocytes. However, this pattern is inconsistently described.
To describe the histological and immunofluorescence characteristics of urticaria and to identify distinctive patterns.
A retrospective study was performed in which the medical files and biopsy specimens of 58 patients with acute and chronic classical urticaria were reviewed. Pathological parameters were quantified.
We recognized 2 distinctive patterns of urticaria: lymphocyte and neutrophil predominant; the former was characterized by a perivascular location, whereas the latter was associated with an interstitial location and a denser infiltrate. Mast cells were relatively sparse, better demonstrated with special stains. Tryptase stain demonstrated more mast cells than Giemsa stain. Extravasated erythrocytes were present in 50% of the cases, but vasculitis was not observed.
Histological findings in classical urticaria show a spectrum of findings from a sparse superficial perivascular to a deep perivascular and interstitial infiltrate. Distinctive groups based on the dominant cell type can be identified, accounting for the similarity to neutrophilic urticarial dermatosis. Lesions may have a purpuric appearance, but leukocytoclastic vasculitis is never present.
*Department of Dermatology, Sheba Medical Center, Tel-Hashomer, Israel; and
†Institute of Pathology, Sheba Medical Center, Tel Hashomer, and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
Reprints: Aviv Barzilai, MD, MSc, Department of Dermatology, Sheba Medical Center, 52621 Tel-Hashomer, Israel (e-mail: email@example.com).
A. Barzilai and L. Sagi are equal contributors.
The authors declare no conflicts of interest.