Local allergic nasal reactions convert to classic systemic allergic reactions: a long-term follow-up

There is poor knowledge about the evolution of the negative skin test in local allergy over time. Does the negative skin test of patients with local allergies remain negative permanently or does it become positive?

We describe our long-term observation concerning the evolution of the negative skin test over time. This is a retrospective, follow-up study using data from the medical records of a group of patients with local allergy. A total of 42 patients aged between 3 and 70 years (median age: 31.5 years) were studied. The duration of follow-up varied from 1 to 27 years. Skin tests were performed using the skin-prick test and intracutaneous techniques for pollen, molds, mites, feathers (goose and duck) and animal danders. Nasal provocation tests were conducted with the same allergens. Additionally, specific IgE in 17 patients was measured by enzyme allergosorbent test.

During the period of observation, the negative skin test reactions converted into positive reactions in 17 patients (40%). In addition to the negative skin reactions, 55% of the patients also presented positive skin reactions. The conversion rate was higher in children and adolescents than in adults. In 4 patients, conversions occurred >7 years after the initial examination. Specific IgE was negative in all but 2 patients, in whom the conversion in the skin test was accompanied by a switch from negative to positive specific IgE.

Conversions from local to classic systemic respiratory allergic reactions appear to be a common phenomenon.