Severe Angioedema With Urticaria Following Distal Pancreatectomy and Splenectomy

Mast cell-mediated angioedema with urticaria presenting without a confirmed trigger is diagnostically challenging in oncology patients. We present a 70-year-old man with an intraductal papillary mucinous neoplasm who developed severe angioedema of the hands, face, tongue, and left eye with urticaria and dyspnea, 5 weeks after robotic distal pancreatectomy and splenectomy. Three concurrent plausible triggers—a new insulin aspart pen, prior cefazolin exposure, and confirmed severe latex allergy—were considered. Historical laboratory data revealed mild peripheral eosinophilia predating the event. The presentation was most consistent with mast cell-mediated histaminergic angioedema; formal mast cell activation syndrome criteria could not be confirmed without acutely obtained serum tryptase. This case underscores that serum tryptase must be obtained within 1 to 4 hours of symptom onset to confirm mast cell activation, and that latex allergy must be excluded as a confounder before attributing reactions to other agents without formal testing.