Histopathologic Features in Urticaria and Urticarial Variants: Plasma Cells Should Be Rare.

Area of Science:

• Dermatopathology
• Immunopathology

Background:

• Urticaria is a common skin condition presenting as transient wheals.
• Microscopic examination of urticaria shows varied inflammatory cells, but plasma cells are rarely reported.
• The frequency of plasma cells in urticaria biopsies lacks systematic study.

Purpose of the Study:

• To investigate the frequency and characteristics of plasma cells in urticaria biopsies.
• To determine if plasma cells are a significant finding in the inflammatory infiltrate of urticaria.

Main Methods:

• A retrospective review of 58 urticaria and urticarial variant cases from 2018-2023.
• Dermatopathologists evaluated H&E stained slides for inflammatory cell types, density, and distribution.

Main Results:

• Eleven of 58 cases (19%) contained rare, scattered plasma cells.
• Predominant inflammatory cells were lymphocytes and neutrophils.
• Inflammation was mostly sparse to moderate in density.

Conclusions:

• Rare plasma cells can be found in urticaria biopsies.
• Abundant or clustered plasma cells are not characteristic of urticaria and may suggest alternative diagnoses.