[What is neutrophilic urticaria?]

Area of Science:

• Dermatology
• Immunology
• Pathology

Background:

• Neutrophilic urticaria (NU) is debated as a distinct nosological entity.
• Some consider NU a variant of urticaria due to polynuclear neutrophil (PNN) presence in histological findings.
• Histological presentation of urticaria can vary based on biopsy timing relative to plaque onset.

Purpose of the Study:

• To evaluate the current evidence regarding neutrophilic urticaria (NU) as a distinct clinical entity.
• To assess the diagnostic criteria, clinical characteristics, and therapeutic responses associated with NU.
• To determine if further research is needed to clarify the status of NU.

Main Methods:

• Review of existing literature on neutrophilic urticaria (NU).
• Analysis of histological findings, particularly the presence of polynuclear neutrophils (PNN).
• Examination of clinical characteristics, associated conditions, and therapeutic responses reported in studies on NU.

Main Results:

• The presence of PNN in urticaria biopsies does not appear to have specific associated clinical features.
• Laboratory inflammatory markers are typically moderate in cases with PNN.
• Therapeutic response data are contradictory, with some studies showing no difference from typical urticaria and one suggesting dapsone efficacy.

Conclusions:

• Available data are insufficient to confirm neutrophilic urticaria (NU) as a separate nosological entity.
• The relationship between cellular infiltrate and therapeutic response in urticaria requires further investigation.
• A prospective study comparing urticaria biopsies is recommended to better characterize NU.