D3.305 - Isolated IgE-Mediated Anaphylaxis to Pine Nut in an adult

Pine nut allergy is considered uncommon, with reported prevalence around 2% in children and 0.5% in adults in the United Kingdom. In Southern Europe, pine nut has been implicated in approximately 3% of paediatric food-induced anaphylaxis cases. However, epidemiological data remain scarce and geographical variability is poorly defined. Pine nut reactions are frequently described in association with sensitization to other tree nuts, and true primary sensitization without molecular evidence of cross-reactivity remains insufficiently characterized. We report a case of severe IgE-mediated anaphylaxis with documented mast cell activation and isolated sensitization to pine nut. 

A 39-year-old male presented with severe anaphylaxis shortly after pine nut ingestion. Clinical manifestations included dyspnoea, labial and periorbital angioedema, hypotension (80/50 mmHg) and hypoxaemia (SpO₂ 91%). He was treated with intramuscular adrenaline, intravenous hydrocortisone, antihistamines and fluid resuscitation, with clinical improvement. Acute and baseline serum tryptase were measured. Total IgE, specific IgE to tree nuts and peanut, and multiplex molecular testing (ImmunoCAP ISAC) were performed. Specific IgE to pine nut was subsequently quantified. 

Acute tryptase was elevated (20.7 µg/L) compared with baseline (4.31 µg/L), confirming mast cell activation. Total IgE was 258 kU/L. Specific IgE to pine nut was 13.7 kUA/L, while specific IgE to hazelnut, walnut and peanut were negative. Molecular testing showed no sensitization to PR-10 proteins, nsLTPs or major storage proteins from other tree nuts. The patient subsequently tolerated peanut ingestion. The patient was prescribed an adrenaline auto-injector and advised strict pine nut avoidance with careful label reading. 

We describe a severe IgE-mediated anaphylaxis to pine nut with biochemical confirmation and isolated sensitization, in the absence of molecular markers of cross-reactivity to other tree nuts. This case highlights the potential severity of primary pine nut allergy and underscores the importance of targeted testing even when standard tree nut panels are negative.