Urticarial syndromes

Synonyms

Urticarial eruptions, urticarial rash.

Definition

There are many dermatoses mimicking urticaria.. In contrast to “urticaria sensu strictu”, “urticarial syndromes” is a set of clinical images which reflect or mimic skin lesions that look like wheals or hives.

Aetiology & Pathogenesis

There are many dermatoses with an urticarial appearance that correspond to different pathogenic mechanisms such as type 1 or 3 immune reactions or are non-allergic (pharmacologic, toxic, chemical) Many of them with an unknown aetiology. They include:

External pathogens
- Insect bites and epizoonoses
- Early stage of contact dermatitis
- Infectious diseases/rashes

Immune dermatoses
- Immunobullous diseases
- Autoinflammatory syndromes
- Neutrophilic dermatosis and autoimmune disorders
- Angioedema

Semantic misnomers
- Urticarial vasculitis
- Urticaria pigmentosa (not primarily urticarial, may evolve urticarial appearance)

Signs & Symptoms

Urticarial lesions last days, itch is variable, sometimes leave a mark with persisting erythema, blood extravasation, hematoma-like or small pigmentation, Sometimes they show scaling. Rarely angioedema is associated, fever sometime is present and is possible that systemic disturbances are key diagnostic features.

Localisation

Urticarial lesions can develop at any body location.

Classification

There is no nosologic classification because of the heterogeneity of the conditions represented.

Laboratory & other workups

There are no specific general laboratory requirements. Some of the diseases need specific diagnostic tests and immunologic and molecular approach.

Dermatopathology

A skin biopsy may be helpful in order to confirm a causative underlying dermatoses.

Course

Depends on the underlying disorder; acute, subacute or chronic persistent or relapsing.

Complications

Depends on the underlying disorder.

Diagnosis

The clinico-pathological correlation is nearly always essential for the diagnosis of urticarial lesions.

Differential diagnosis

See aetiology & pathogenesis.

Prevention & Therapy