From Avoidance to Action: Emerging Therapies for Management of Chronic Inducible Urticaria - Episode 1
CIndU Subtypes, Overlap With CSU, and Practical Provocation Testing
Chronic inducible urticaria spans many subtypes and frequently overlaps with chronic spontaneous urticaria, making careful history taking and pragmatic provocation testing central to an accurate diagnosis.
Welcome back to another HCPLive Peer Exchange series. In "CIndU Subtypes, Overlap With CSU, and Practical Provocation Testing," moderator David Cotter, MD, PhD is joined by Shannon Trotter, DO, FAOCD, FAAD and Lindsey Finklea, MD to open the series on chronic inducible urticaria.
Dr. Cotter opens by asking Dr. Trotter to outline the principal CIndU subtypes. She identifies symptomatic dermographism, cholinergic urticaria, and cold urticaria as the three most common forms seen in practice. Symptomatic dermographism is more common than many clinicians assume, affecting an estimated 2% to 5% of the population. Beyond these three, she notes heat, solar, delayed pressure, aquagenic, vibratory, and contact urticaria as less common subtypes. Dr. Cotter adds that symptomatic dermographism often surfaces incidentally during routine skin examinations, in patients who never realized they had it.
Dr. Finklea then addresses overlap between CIndU and chronic spontaneous urticaria (CSU). She estimates that 20% to 30% of patients have symptoms of both conditions, which makes the clinical picture harder to untangle. A standardized history and physical examination is therefore essential. When patients are strong historians, the trigger is usually obvious, but vague histories demand more detective work.
She illustrates the challenge with a patient who reports hives at the beach. That reaction could reflect dermographism from sand, solar urticaria, cholinergic urticaria from sweating, or even delayed pressure urticaria from being buried in sand. In such cases, clinicians rely on provocation testing to confirm the trigger.
Dr. Finklea acknowledges that most dermatology clinics lack formal provocation equipment. Clinicians often improvise with the back of a pen or a tongue depressor, an ice cube test, or hot running water. When standardized tools are available, options include the FricTest 4.0 for dermographism, TempTest for cold and heat urticaria, and pulse-controlled ergometry for cholinergic urticaria. These standardized approaches produce reproducible, predictable responses. Dr. Cotter agrees that provocation testing becomes especially valuable when overlapping features obscure the trigger.
The next episode in this series, "Laboratory Workup and Mast Cell Pathophysiology in CIndU," features Dr. Finklea walking through laboratory evaluation and the immune pathways that converge on the mast cell.
