Skin reaction patterns in cholinergic urticaria

Background: Skin reaction patterns vary across patients with cholinergic urticaria (CholU), but their definition, prevalence, and clinical significance remain ill characterized. Methods: Patients with CholU underwent pulse-controlled ergometry provocation testing to analyze skin reaction patterns and their correlation with location, onset, severity, sweating behaviour, clinical features, disease control, and quality of life (QoL) impairment. Results: Based on the size, color, spacing, and shape of wheals as well as their surrounding skin responses, we identified six distinct types of CholU skin reactions, which differed in prevalence, from 83% (Type I) to 11% (Type VI) of patients affected. Almost all patients (94%) had ≥1 type of skin reaction pattern. Sweating was reduced in the majority of CholU patients and most prominently reduced in patients with Type VI skin signs (very small, round, red, widely spaced wheals with surrounding anemic halo), which emerged exclusively on the extremities. Type V skin signs (large, irregular, anemic, widely spaced wheals with moderate size erythema) were associated with the most severe clinical presentation and poorest QoL. Conclusions: Our analysis showed that most patients have more than one type of skin reaction patterns and that different skin signs are linked to distinct features. Future studies should determine any links between treatment response and types of skin signs in CholU.