Local allergic rhinitis in children: identification and characterization in a specialty outpatient clinic.

Summary: Background. Local Allergic Rhinitis (LAR) is a phenotype defined by rhinitis symptoms with negative responses to systemic sensitization tests but with an exclusively nasal allergic inflammatory response. Data on the pediatric age group is scarce, and no Latin American data has been published so far. Methods. Nasal Allergen Challenge (NAC) was performed with Dermatophagoides pteronyssinus and Blomia tropicalis in six- to 18-year-old patients diagnosed with rhinitis and no systemic sensitization. NAC was monitored using subjective parameters and acoustic rhinometry. The study aimed to identify LAR in child and adolescent subjects previously diagnosed with non-allergic rhinitis (NAR) in a Brazilian specialty outpatient clinic (Allergy and Immunology). Results. During the study period, we analyzed 758 skin prick tests (SPT). Of those, 517 (68.2%) were diagnosed with rhinitis. Among those, 18.4% (95/517) had a negative SPT, meeting the criteria for inclusion in the study. Twenty-five patients underwent NAC, and 40% (10/25) of them, previously considered to have NAR, had a positive test and were reclassified as having LAR. Based on the analyzed characteristics, clinically differentiating LAR from NAR was impossible. Conclusions. This study represents the first investigation of LAR in child and adolescent subjects in Latin America, contributing significantly to the understanding of its prevalence and characteristics in this geographic area. Among a subgroup of patients lacking systemic sensitization submitted to NAC, 40% (10/25) demonstrated a positive NAC with Dermatophagoides pteronyssinus and Blomia tropicalis, warranting their reclassification to LAR. NAC with multiple allergens has been proven safe and viable in pediatric populations, affirming its critical role in the accurate diagnosis of LAR.