Recurrent Intestinal Angioedema with Normal C1-Inhibitor: A Case Report.

: Angioedema is a non-pitting edema of the submucosal layer which can be acquired or inherited and usually presents with hives. Intestinal angioedema is rare and can mimic other acute gastrointestinal disorders. It is typically associated with a lack or dysfunction of C1-inhibitor, with a small number of cases having normal C1-inhibitor function.

Acute/baseline ratios of all 3 MC mediator metabolites can enhance diagnosis and management of mast cell activation syndrome.

Background: Mast cell (MC) activation syndrome (MCAS) can be a challenge to diagnose and treat despite the near continuous appearance of publications outlining specific criteria. Follow-up of the clinical responses to treatment is often lacking, and confirmation that leukotriene C (LTC) is an active participant in MCAS has been overlooked.

Objective: Three patients with MCAS characterized by anaphylaxis are presented to illustrate (1) the value of contemporaneous urinary mediator sampling during MCAS in addition to serum tryptase measurements and (2) substantiation of the fact that not only can LTC (measured metabolite LTE) be the highest metabolite measured, but (3) blockade of the LTE receptor can contribute to symptom prevention.