Unusual reactions to hymenoptera stings: what should we keep in mind?

This review includes a variety of extremely rare and unusual hymenoptera sting (HS) circumstances with regard to sting localization, geographic region, massivity of multiple stings, and particularly related to clinical symptoms. Such reactions occur in a temporal relationship to HS (s), differ from typical allergic symptomatology, and sometimes need follow-up during many months. With respect to pathogenesis, the major mechanisms involved are toxic, autoimmune, and other delayed immunological ones. While delayed inflammatory symptoms of the nervous system are considered as delayed hypersensitization or autoimmune entities, generalized rhabdomyolysis and consecutive acute kidney injury is considered a toxic reaction, mostly induced by massive envenomation to wasps or "Africanized" bees. Hemorrhagic episodes of targeted organ (s) could be additional potential risk for acute kidney injury, while the bee venom-induced hemorrhage is proposed to be a nonimmune-mediated anaphylactic symptom. The hemodynamic involvement of vital organs and systems with hypoxia and hypovolemia together with simultaneous immunoglobulin E (IgE) sensitization are considered potential indications for venom immunotherapy. In contrast, patients who have experienced various complications with unknown or nonallergic mechanisms should be informed about the importance of epinephrine's use and additional measures on future sting avoidance. In conclusion, although unusual reactions are extremely rare, it is important to keep them in mind.