Matthew P. Giannetti

Purpose of Review Biphasic anaphylaxis is a variant of anaphylaxis characterized by recurrence of symptoms after initial resolution of anaphylaxis. It was first described in the mid 1990s by Popa and Lerner. Our understanding of the pathophysiology and epidemiology of the condition has advanced considerably since then. The purpose of this manuscript is to review the literature surrounding biphasic anaphylaxis while highlighting key works and recent advances. Recent Findings Prior studies have estimated biphasic anaphylaxis occurs in 0.4–20% of anaphylaxis episodes. The wide range may be related to differences in anaphylaxis diagnostic criteria which was inconsistent across studies. Recently identified risk factors for occurrence of biphasic anaphylaxis include severe initial symptoms including hypotension or hypoxia, delay in epinephrine use, and greater than one dose of epinephrine required to treat symptoms. Summary Despite our progress to better understand biphasic anaphylaxis, there remain gaps in the literature. This article aims to review the recent literature including, epidemiology, risk factors, and management of biphasic anaphylaxis.

Mastocytosis is a myeloproliferative neoplasm characterized by abnormal proliferation and activation of clonal mast cells typically bearing the KITD816V mutation. Symptoms manifest due to the release of bioactive mediators and the tissue infiltration by neoplastic mast cells. Mast cell activation symptoms include flushing, pruritus, urticaria, abdominal cramping, diarrhea, wheezing, neuropsychiatric symptoms, and anaphylaxis. Up to 50% of patients with mastocytosis report a history of provoked and unprovoked anaphylaxis, with Hymenoptera venom and drugs the most common culprits. NSAIDs, antibiotics, vaccines, perioperative medications, and radiocontrast media are often empirically avoided without evidence of reactions, depriving patients of needed medications and placing them at risk for unfavorable outcomes. The purpose of this review is to highlight the most common agents responsible for adverse drug reactions in patients with mastocytosis, with a review of current epidemiology, diagnosis, and management of drug hypersensitivity and Hymenoptera venom allergy.