Hymenoptera allergy, difficulties in differential diagnosis: a case report

The diagnosis of hymenoptera venom allergy can be particularly challenging, with the clinical history serving as a fundamental tool to guide the identification of the culprit insect. However, patient-reported visual recognition is often inaccurate and may lead to diagnostic errors unless supported by specific immunoallergological testing.

A 37-year-old man who, during a stay in Taramundi (Asturias, Spain), sustained an insect sting that he visually identified as Nomada flava. Ten minutes later, he developed Müller grade III anaphylaxis, with loss of consciousness, angioedema, and vomiting. The allergologic evaluation revealed double sensitization to Vespula spp. and Polistes dominula through skin testing and specific IgE measurement, with no evidence of sensitization to Apis mellifera. Immunoblot analysis demonstrated serum reactivity directed against Polistes dominula venom, mainly to component Pol d 1. Based on these findings, a diagnosis of Polistes dominula venom allergy was established, and species-specific venom immunotherapy was prescribed. The patient was also diagnosed with mast cell activation syndrome, confirmed by bone marrow examination.

This case underscores the need for a comprehensive allergologic workup to accurately identify the implicated species and guide appropriate venom immunotherapy, as patient-reported visual recognition of the stinging insect may be unreliable.