In a study Steven Kossard, FACD; Ian Hamann, FACD; Barbara Wilkinson, BSc, concluded that urticarial dermatitis may represent a useful term for a subset of a reaction pattern designated most commonly as dermal hypersensitivity by pathologists. The term is not commonly used, and requires definition to determine whether it is clinically relevant.
There is a group of patients who present with urticarial plaques and papules that may resemble urticaria, but the individual lesions last longer than 24 hours and often last for days. The lesions are usually intensely pruritic, and there may be a predominant papular element or urticated erythema with excoriations.
Biopsy results from the urticated areas typically reveal upper dermal perivascular lymphocytes and eosinophils with or without neutrophils, but no gross epidermal vesiculation or parakeratosis. This particular combination of histological features has been designated as urticarial dermatitis in the laboratory for at least 5 years.
The term dermal hypersensitivity reaction pattern has also been used by pathologists to describe this finding.
In this study, authors reviewed their experience in using urticarial dermatitis as a histological term and examined archived reports to determine whether the term may be useful for clinicians to help identify a subset of the dermal hypersensitivity reaction pattern.
The primary aim of the study was to explore the use of urticarial dermatitis as a term for the clinician and the pathologist. The term urticarial dermatitis seems to be useful clinically and histologically, as the descriptive term highlights recognizable features.
Although the clinical presentation is not restricted to a specific entity, eczema and drug reaction seem to be the most frequent clinical associations.
In a subset, urticarial dermatitis remains as a sole reaction pattern.
The pathophysiological features of urticarial dermatitis remain to be explored, but may represent a persistent T helper cell 2 reaction that is usually transitory and precedes the dominant T helper cell 1 cytokine profile, particularly in atopic dermatitis.
In many patients with the clinical diagnosis of urticarial dermatitis, clinicopathological correlation can be achieved, and these form a subset that is mixed within the larger group classified as having a dermal hypersensitivity reaction pattern.