D3.417 - "Comprehensive Allergological Evaluation and Management of Severe Anaphylaxis to Vespid Venoms: A Case Study"
Background
Diagnosis of hymenoptera venom (HV) hypersensitivity may be challenging, especially in cases of sensitization to several vespids. In severe HV reactions, mast cell disorders (MCD) must be evaluated.
Method
In august 2021, a 50-year-old male experienced generalized erythema with no hives or pruritus, loss of consciousness and vomiting after being stung by ten vespids, identified by the patient as common wasps and velutina. He received two 0.4mg doses of intramuscular epinephrine, corticosteroids and antihistamines, and was transferred to the emergency room.
Subsequent allergological study included skin test (prick and intradermal, ALK-Abelló), total and specific IgE (Thermofisher) and CAP inhibition assay. On the other hand, MCD study consisted of peripheral blood and bone marrow work-up with cytology, flow-cytometry, immunohistochemistry and molecular biology. Digital PCR (Thermofisher) for hereditary alpha-tryptasemia (HAT) was also performed.
Results
Skin intradermal tests (ID) were positive for vespula sp. (10mm) and polistes dominulus (6mm) as well as the molecular diagnosis (Table 1).
|
Table 1: Molecular diagnosis |
||||||||
|
Total IgE (KU/L) |
sIgE Vespula (KU/L) |
sIgE Polistes (KU/L) |
sIgE Ves V1(KU/L) |
sIgE Ves v5 (KU/L) |
sIgE Pol d5 (KU/L) |
MUFXF3 (KU/L) | Tryptase (ucg/L) | |
| 08/2021 | 26 | |||||||
| 11/2021 | 647 | >100 | >100 | 44 | >100 | >100 | 0 | 11.1 |
| 10/2023 | 67.9 | 13.8 | 9.46 | 6.8 | 16.6 | 6.27 | 0 | 9.8 |
CAP inhibition assay showed greater heterologous inhibition with vespula (98%) than with polistes (48.5%) which suggests a primary sensitization to vespula with cross-reactivity to polistes, rather than true double sensitization.
Due to a REMA score = 4 the patient was referred to a specialized MCD center for further evaluation. Peripheral blood and bone marrow work-up showed moderate increase of mast cells, over 50% of them with atypical morphology, with no aggregates, a normal immunophenotype and negative D816V C-KIT mutation. Clonal MCD was therefore ruled out as well as HAT (genotype 1 alpha-3 beta).
With the previous results vespula-specific immunotherapy was initiated in 01/2023, with no adverse reactions.
Conclusion
This case underscores the importance of a comprehensive allergological evaluation in accurately determining HV sensitization profiles and personalizing venom immunotherapy. In this case the severity of the reaction was probably due to the high number of stings rather than to a MCD. Nevertheless, elevated serum tryptase and some findings in bone marrow biopsy deserve further follow-up of the patient.
