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Wise et al.

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(NARESMA). 1097 Idiopathic rhinitis is also characterized by high levels of eosinophils and mast cells in some patients. 1098 Overlapping forms may occur. 1099 NC is 1 method of diagnosing NAR and has been used to differentiate between variants in experiments. 1100 However, few studies investigating the diagnostic performance of NC in diagnosing AR or NAR are available (Table VIII.I-1). • Aggregate Grade of Evidence: C (Level 3b: 3 studies; Level 4: 1 study; Table VIII.I-1). Nasal histology as assessed by biopsies of the nasal cavity was the only technique to study tissues and cells in patients with AR for many decades. In the 1990s, biopsy-based investigations allowed researchers to define the role of the different inflammatory cells in AR. 379 The original technique begins by spraying a local anesthetic and topical vasoconstrictor into the nasal passages. After anesthesia has taken effect, a piece of tissue is removed from the middle turbinate using small punch biopsy forceps. After immediately placing the tissue in buffered formalin, each specimen can then be stained with various reagents to detect different tissue components and cells. 1101 Reagents used include Giemsa, hematoxylin/eosin, periodic acid-Schiff, Masson trichrome, azure A, and chloroacetate esterase. 299,415,1101 After staining, the slides are examined by an optical double-headed light microscope, using a grid reticule divided into 100 squares to quantitate cells and tissue per square millimeter. The introduction of NC made it possible to obtain the similar information as histology, but without the associated discomfort and potential risk for bleeding. Further, NC allows for sequential sampling where histology does not. In addition, when Lim et al. 415 compared nasal histology with cytology in patients with perennial and seasonal rhinitis compared to controls, the results suggested that nasal secretions and the nasal mucosa represent 2 distinct cellular compartments. Specifically, following allergen challenge an influx of inflammatory cells was detected by cytology, while the epithelial layer assessed by histology was unchanged from baseline. 415 In 2005, Howarth et al. 1102 stated that, compared to simple techniques such as NC or nasal lavage, nasal biopsy requires expertise both in tissue sampling and in biopsy processing, thus being applicable only in specialist centers. This issue, as well as the previously reported drawbacks, makes nasal histology a technique of interest in the research on pathophysiology of AR but hardly feasible for routine clinical practice. Table VIII.I-2 shows the available studies on AR pathophysiology as evaluated by nasal histology. • Aggregate Grade of Evidence : B (Level 1b: 8 studies; Level 3b: 3 studies; Table VIII.I-2).

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IX. Management IX.A. Allergen avoidance

Allergen avoidance and environmental controls (ECs) are frequently discussed as part of the treatment strategy for AR, along with pharmacologic management and AIT. AR patients are keen to learn about avoidance measures and ECs, especially those who wish to avoid

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