Unusual cold-induced disorders: cold-dependent dermatographism and systemic cold urticaria

Area of Science:

• Dermatology
• Allergy and Immunology

Background:

• Standard diagnostic tests for cold urticaria and dermatographism can fail to identify certain cold-induced hypersensitivity disorders.
• Two patients presented with symptoms suggestive of these conditions, but initial testing was inconclusive.

Observation:

• One patient exhibited dermatographism only after skin chilling post-scratching, with elevated histamine levels during urticaria.
• The second patient experienced generalized, anaphylactoid urticaria triggered by systemic cold exposure, also with elevated histamine levels.

Findings:

• Two distinct cold-dependent disorders were identified, characterized by unique triggers and histamine level changes.
• The second patient also showed augmented skin reactivity to cold during urticarial episodes.

Implications:

• These newly defined cold-induced disorders should be considered in the differential diagnosis for patients with suspected cold urticaria or dermatographism.
• Negative standard test results warrant further investigation into these atypical cold hypersensitivity conditions.