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Wise et al.

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Sensitization vs clinical allergy— Monosensitization is sensitization (as indicated by positive reactions on standardized SPTs or serum sIgE levels) to only 1 allergen, such as grass pollen, tree pollen, HDM, or cat dander (even though extracts of these concentrates contain numerous diverse polypeptides). 31 Monoallergy is defined as a single sensitizing allergen causing clinical allergy symptoms. Polysensitization is sensitization to 2 or more allergens. Polyallergy is affirmed clinical symptoms to 2 or more sensitizing allergens. Findings of allergy testing, either skin testing or sIgE must be correlated with clinical symptoms to identify the allergen(s) likely responsible for the symptoms. 32 Allergen challenges (ie, nasal provocation testing, conjunctival challenge, or allergen challenge chambers (ACCs)) can reproducibly confirm the clinical significance of a sensitized allergen, but these tests may be difficult to perform, subjective, and limited by irritant effects. 33 Allergy skin testing and sIgE titer must be carefully interpreted at the patient level, and can also be valuable at the population level when evaluating sensitization for epidemiological studies. 34 With increasing availability of component-resolved diagnosis (CRD), physicians will have a more objective means of identifying clinically relevant allergens and distinguishing true co-sensitization from polysensitization due to cross-reactivity. (See section VIII.F.6. Evaluation and diagnosis - In vitro testing - Component resolved diagnosis (CRD) for additional information on this topic.) The symptoms of AR may be similar to symptoms of other types of sinonasal disease, and at times multiple types of rhinitis may coexist. It is important to correctly determine the etiology of rhinitis to appropriately treat the patient and have the best chance of resolving his or her symptoms. In the following sections, a discussion of the differential diagnosis of AR is presented, along with a description of how each rhinitis entity differs from AR. Of note, this section on AR differential diagnosis is specific to various etiologies of rhinitis. Other entities that may enter into the differential diagnosis of AR, such as structural sinonasal conditions (ie, deviated septum), tumors, and cerebrospinal fluid leak are not discussed here (Table III.C). III.C.1. Drug-induced rhinitis— Rhinitis secondary to systemic medications can be classified into local inflammatory, neurogenic, and idiopathic types 35,36 (Table III.C.1). The local inflammatory type occurs when consumption of a drug causes a direct change in inflammatory mediators within the nasal mucosa. The neurogenic type occurs after use of a drug that systemically modulates neural stimulation, leading to downstream changes in the nasal mucosa. Idiopathic drug-induced rhinitis is used to classify drugs without a well defined mechanism contributing to symptoms. Topical nasal decongestants can cause drug induced rhinitis, known as rhinitis medicamentosa (RM). (See Section III.C.2. Definitions, classifications, and differential diagnosis - Allergic rhinitis differential diagnosis - Rhinitis medicamentosa (RM) for additional information on this topic.)

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III.C. Allergic rhinitis differential diagnosis

Local inflammatory type.: Systemic ingestion of non-steroidal anti-inflammatory drugs (NSAIDs) in patients with a disorder of eicosanoid synthesis can result in rhinitis and nasal

Int Forum Allergy Rhinol . Author manuscript; available in PMC 2020 June 10.