Watch Dr. Dareen Siri emphasize key points from her panel discussion, Complex Eczema/Urticaria/Allergy Cases, at the 6th Annual Elevate-Derm Alliance Conference at the JW Marriott Water Street in Tampa, Florida.

In this video

In conversation with dermatology NP Veronica Richardson, Dr. Siri — an allergist and immunologist and CEO/founder of Midwest Allergy, Sinus and Asthma — tackles the patient who arrives with recurrent flushing and skin lesions, sometimes announcing they suspect a mast cell disorder. She notes these have become "buzz words" thanks to social media, but the recognition (and emerging treatments) is real. Her advice: when a patient fits neatly in the CSU box, treat CSU — but when traditional medications help yet fall short, ask whether this is "not just a CSU patient alone."

She frames the tell-tale constellation as a history of anaphylaxis (especially medication, food, or hymenoptera stings with cardiovascular collapse), plus GI symptoms in the hyperactive, diarrhea-predominant pattern, layered on top of the skin findings. Workup starts simply with a tryptase level and, when suspicion holds, high-sensitivity D816V KIT mutation testing — positive in over 90% of indolent systemic mastocytosis — sometimes repeated over years when the index of suspicion stays high.

  • A clear CSU picture is CSU — reconsider mast cell disease when standard therapy helps but doesn't get patients where you want them, or when flushing dominates without true urticaria.
  • Look for the constellation: history of anaphylaxis (drug, food, or bee/wasp sting, especially with cardiovascular symptoms), plus frequent GI symptoms in the diarrhea-predominant "hyperactive" pattern, on top of skin findings.
  • Start with two simple blood tests: a tryptase level (normal under 8) and, if elevated or suspicion is high, high-sensitivity D816V KIT mutation testing.
  • A normal tryptase doesn't rule it out — some patients with the mutation have baseline-normal tryptase, so consider repeating both tests over time when suspicion is high.
  • Consider referral to an allergist/immunologist first to help triage before invasive bone marrow biopsy; a negative tryptase and negative high-sensitivity KIT test more than once makes an invasive workup a hard sell.