Cholinergic Urticaria: Subtype Classification and Clinical Approach

Abstract

Cholinergic urticaria (CholU) is a subtype of chronic inducible urticaria with a chief complaint of itching and/or stinging, painful papular wheals that develop simultaneously with sweating. This review specifically focuses on several subtypes of CholU and specifically investigates the relationship between CholU and anhidrosis. We review recent publications and update the evidence around CholU, including the epidemiology, clinical features, diagnostic approaches, physiopathology, subtype classification, and therapeutic approaches. Multiple mechanisms contribute in a complex manner to the development of CholU, including histamine, sweat allergy, cholinergic-related substances, poral occlusion, and hypohidrosis/anhidrosis. A new schematic of the currently known pathological conditions has been created. Specific methods for diagnosing CholU, a provocation test, and evaluation methods for disease severity/activity and disease burden of CholU are summarized. The characteristics of the diseases that should be differentiated from CholU and examination methods are also summarized. The primary finding of this review is that CholU should be categorized based on the etiology and clinical characteristics of each subtype to properly manage and treat the disease. This categorization leads to improvement of therapeutic resistance status of this disease. In particular, a sweating abnormality should be given more attention when examining patients with CholU. Because CholU is not a homogeneous disease, its subtype classification is important for selection of the most suitable therapeutic method. Further elucidation of the pathophysiology of each subtype is expected.

A single-blind, randomized, crossover study on the efficacy of icatibant for sweating-induced dermal pain (icatibant for sweating-induced dermal pain)

“…To induce dermal pain, both lower legs will be placed in warm water (~43°C) for 30 minutes. [13] This condition of loading is enough to induce sweating in healthy subjects, commonly experienced in daily life, and thus, non-excessive in terms of intensity and duration. The VAS score, a widely used pain rating scale, will be employed to measure the intensity of the pain.…”

“…After collecting patients' background data, both lower legs will be subjected to thermal load by placing them in warm water (~43°C) for 30 minutes to induce dermal pain. [13] Scheduled examinations and blood sampling will be performed before and after thermal loading. The examinations include VAS for pain, distribution and duration of dermal pain, VAS for itching, and presence or absence of eruption.…”

Clozapine-induced cholinergic urticaria: a case report

“… 16 The heat urticaria, a rare inducible urticaria variant, presents erythematous wheals restricted only to the heated area. 17 In addition, CU was clinically differentiated from aquagenic urticaria, provoked by water contact, and adrenergic urticaria, induced by stress or trauma. Adrenergic urticaria is typified by wheals surrounded by a vasoconstrictive white halo, 18 a presentation not observed in our patient.…”

Chronic inducible urticaria a particular form of chronic urticaria

“…Some authors have proposed categorizing cholinergic urticaria with angioedema as related to sweat allergy, involving IgE-mediated type I allergic reactions to components within the patient's sweat, which could explain the systemic reactions. 7,8 Given the distinct clinical presentations of CIndU subtypes, comprehending their pathophysiology and identifying therapeutic targets will differ. There is likely significant | 453 SORIA importance in distinguishing between these subcategories of CIndU since diverse causal factors necessitate varying therapeutic approaches.…”

“…However, statistical significance was not established ( p = 0.053 and p = 0.058, respectively). Some authors have proposed categorizing cholinergic urticaria with angioedema as related to sweat allergy, involving IgE‐mediated type I allergic reactions to components within the patient's sweat, which could explain the systemic reactions 7,8 …”