The Histopathology of Urticaria Revisited-Clinical Pathological Study

Area of Science:

• Dermatopathology
• Immunology

Background:

• Classic urticaria histology involves dermal edema and sparse inflammatory cell infiltrates.
• Histopathological findings in urticaria are often inconsistently described.
• Understanding urticaria's histological spectrum is crucial for accurate diagnosis.

Purpose of the Study:

• To characterize the histological and immunofluorescence features of urticaria.
• To identify distinct diagnostic patterns within urticarial lesions.

Main Methods:

• Retrospective analysis of 58 patients with acute and chronic urticaria.
• Review of medical records and biopsy specimens.
• Quantification of pathological parameters.

Main Results:

• Two predominant histological patterns identified: lymphocyte-rich and neutrophil-rich.
• Lymphocyte-predominant pattern showed perivascular infiltrate; neutrophil-predominant showed interstitial infiltrate.
• Mast cells were sparse but better visualized with tryptase stain; no vasculitis observed.

Conclusions:

• Urticaria exhibits a spectrum of histological findings, from superficial to deep infiltrates.
• Distinct cellular patterns can be identified, aiding differentiation from conditions like neutrophilic urticarial dermatosis.
• Purpuric lesions may occur, but leukocytoclastic vasculitis is absent in classical urticaria.