Nasal eosinophilia in allergic and nonallergic rhinitis: usefulness of the nasal smear in the diagnosis of allergic rhinitis.

Diagnostic nasal cytology has been advocated for use in distinguishing allergic from nonallergic rhinitis. We sought to determine prospectively the frequency of nasal eosinophilia (NE) in 100 patients in whom having allergic rhinitis (AR), nonallergic rhinitis, and other atopic conditions not involving the respiratory tract have been diagnosed. A nasal smear was obtained from consenting adults using the Rhino-Probe curette. Patients taking local or systemic corticosteroids, those with chronic rhinitis associated with aspirin sensitivity, and those with sinusitis were excluded. All cytograms were coded and read by a single "blinded" investigator. NE was considered significant if greater than 20% of sampled cells were eosinophils. Twenty-six of 61 (43%) patients with AR had NE. No NE was detected in the control population or in the skin test negative group of patients in whom having nonallergic rhinitis was diagnosed. One of 16 patients with allergic disease not involving the respiratory tract exhibited NE; this patient had atopic dermatitis with peripheral eosinophilia. No cases of eosinophilic nonallergic rhinitis were detected. There was no significant correlation of symptoms or the number of positive skin tests with NE. These data suggest that the nasal smear for eosinophils is an insensitive but specific test for the diagnosis of allergic rhinitis, when patients with nasal polyposis and aspirin sensitivity and/or negative skin tests are excluded.