Case Report: Perioperative immediate hypersensitivity involves not only allergy but also mastocytosis

We report a case of drug-induced immediate hypersensitivity occurring after atracurium injection in a patient with cutaneous mastocytosis. A 69-yr-old woman was scheduled for hysterectomy. She was premedicated with hydroxyzine, and anesthesia was induced with sufentanil, propofol, and atracurium. Within two to three minutes following the injection of atracurium, the patient experienced an episode of generalized erythema and arterial hypotension associated with tachycardia. No bronchospasm was observed. Her cardiovascular signs resolved spontaneously within five minutes, while her cutaneous signs disappeared within 30 min. Anesthesia and surgery remained uneventful. The patient's serum tryptase levels were measured at different time points following the clinical reaction. An in vitro flow cytometry-based basophil activation test was performed with atracurium, and in vivo skin tests to latex and all drugs which were administered just before the clinical reaction were also done. The serum tryptase showed increased concentrations that remained elevated for 24 hr, 48 hr, and even four weeks after the clinical reaction. Atracurium did not induce either CD63 or CD203c upregulation, and the skin tests were negative in response to the medications received (propofol, sufentanil, and atracurium) as well as to latex. Allergic hypersensitivity to atracurium was ruled out. Increased tryptase concentrations following the clinical reaction, persistent increased levels of basal serum tryptase, and negative skin tests suggested the onset of mast cell degranulation in a patient with mastocytosis. Immediate reaction occurring in patients with mastocytosis should be investigated in order to identify the mechanism of the reaction, either histamine release due to the disease itself or due to a concurrent drug/agent-induced IgE-mediated mechanism.