Nasal Cytology as a Diagnostic Tool for Local Allergic Rhinitis

Background Local allergic rhinitis (LAR) is characterized by chronic rhinitis with localized nasal allergic response to allergens in the absence of systemic immunoglobulin (IgE)-mediated disease assessed by skin prick test (SPT) or specific serum IgE level. Nasal provocation test (NPT) is the gold standard for the diagnosis of LAR. Nasal eosinophilia is a known inflammatory marker in allergic rhinitis. We hypothesized that nasal eosinophilia can be used as a screening tool for LAR. Objective To determine the applicability of nasal eosinophilia as a diagnostic tool for LAR. Methods Forty-eight perennial nonallergic rhinitis (NAR) patients with SPT negative were recruited. Nasal cytology analysis was performed. NPTs with 3 allergens (mixed mites, mixed cockroaches, and Bermuda grass) were performed to diagnose LAR. Nasal symptoms combined with nasal patency were used to determine the results of NPT. The sensitivity, specificity, positive predictive value, and negative predictive value of nasal eosinophilia as a diagnostic tool of LAR were calculated. Results LAR was diagnosed in 41.6% of the NAR patients. Nasal eosinophilia was found in 58% of the NAR patients. The sensitivity of nasal eosinophilia for diagnosing LAR was 80%, the specificity was 57.14%, the positive predictive value was 57.14%, and the negative predictive value was 80%. The most common allergen of LAR was mixed mites. Conclusion Nasal eosinophilia on nasal cytology was a good screening tool for diagnosing LAR because of its high sensitivity and simplicity of the procedure. Unfortunately, the low specificity of nasal eosinophilia makes the NPT necessary for confirmation of LAR.