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Absence of angioedema in Hymenoptera sting reactions may indicate mastocytosis

The absence of urticaria or angioedema in reactions to Hymenoptera stings with hypotension may represent the most relevant factor in identifying patients with mastocytosis, according to recent study results.

“Our results highlight that the characteristics of severe [Hymenoptera venom allergy (HVA)] episodes with hypotension in the absence of urticaria/angioedema might represent the most relevant factor to identify those patients with HVA and [clonal mast cell disorders (CMD)], regardless of baseline tryptase levels,” Giovanni Passalacqua, MD, of the University of Genoa, and colleagues wrote.

Giovanni Passalacqua

Researchers evaluated 22 patients for suspicion of CMD after a severe reaction to a Hymenoptera sting between September 2012 and November 2013. Researchers identified patients with at least one or more episodes of anaphylaxis with documented hypotension, loss of consciousness, or both without skin lesions and with serum basal tryptase [SBT] levels less than 11.4 ng/mL.

Eleven of the patients experienced more than one anaphylactic episode. Indolent systemic mastocytosis was diagnosed in 15 of 16 patients plus one case of monoclonal mast cell activation syndrome.

Patients with confirmed CMDs had higher SBT levels (P=.03) and seldom showed angioedema/urticaria during the anaphylactic event (P=.004).

“As a speculative aspect, we can hypothesize that patients with no skin involvement, normal SBT levels, and anaphylaxis with ascertained hypotension and loss of consciousness caused by Hymenoptera stings should undergo a bone marrow examination to detect a possible CMD,” the researchers wrote.

Disclosure: The researchers report no relevant financial disclosures.