Cholinergic urticaria

This code identifies a specific type of physical urticaria characterized by small, itchy wheals that appear in response to an increase in body temperature, often triggered by exercise, hot baths, or emotional stress. The condition is mediated by acetylcholine release, leading to mast cell degranulation. Patients typically experience a burning, stinging, or itching sensation prior to the eruption of lesions.

Use this code when documentation clearly indicates a diagnosis of cholinergic urticaria, distinguishing it from other forms of urticaria. This diagnosis is typically made based on clinical presentation and a positive methacholine challenge test or exercise challenge test. Documentation should specify the trigger and the characteristic rash.

• Differentiate from other forms of urticaria (e.g., cold urticaria, dermatographism) which have distinct ICD-9-CM codes.
• Ensure the documentation supports the cholinergic etiology, not just a general diagnosis of "hives" or "urticaria."
• Consider any associated systemic symptoms or anaphylactic reactions, which may require additional coding.