Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Role of aspirin desensitization in the management of chronic rhinosinusitis Habib Rizk Introduction The triad of sinusitis, bronchial asthma, and aspirin intolerance is known as Widal’s syndrome, Samter’s triad, and aspirin-exacerbated respiratory disease (AERD). The most recent consensus nomenclature describing acetylsalicylic acid (ASA)-induced respiratory reactions is nonallergic hypersensitivity reaction. Patients with chronic rhinosinusitis (CRS) with nasal polyps are more likely to have aspirin hypersensitivity or asthma than the general population. Nasal polyps are reported in up to 70% of aspirin intolerant patients with asthma, whereas their prevalence is only 4% in the general population. In sensitive individuals, even a very small single dose of aspirin or other cyclooxygenase-1 (COX-1) inhibitor can cause rhinorrhea, bronchospasm, and shock [1 ]. These patients usually have a more aggressive sinonasal disease with need for multiple endoscopic sinus surgery over the years. Aspirin desensitization, although unpopular because of the fear of severe reactions, has proven to be a valuable therapeutic tool in these severe recalcitrant cases. This paper sums up the pathogenesis of AERD, explores the diagnostic methods that can be used, and finally reviews the role of aspirin desensitization specifically in the treatment of upper airway disease with focus on the mechanism of action of this underutilized treatment modality. Pathogenesis: nonallergic hypersensitivity reaction In 1971, Vane discovered the effects of ASA and NSAIDs on inhibition of COX enzymes in the metabolic cascade of arachidonic acid metabolism. The COX enzymes exist in at least two isoforms, COX-1 and COX- 2. COX-1 is expressed in most mammalian cells. COX-2 is induced during inflammation. COX 3 is expressed in the brain and heart. In 1980, the first report of a second metabolic pathway for arachidonic acid metabolism also involved in inflammation was published. This pathway involves 5-lipoxygenase enzyme induction of leukotriene syn- thesis. Leukotrienes C, D, and E4 [(LTC, LTD, and LTE4)] are potent mediators of chemotaxis of Department of Otolaryngology/Head and Neck Surgery, Hotel-Dieu de France Hospital, Faculty of Medicine, Saint-Joseph University, Beirut, Lebanon Correspondence to Habib Rizk, MD, Department of Otolaryngology/Head and Neck Surgery, Hotel-Dieu de France Hospital, Alfred Naccache Street, Beirut, Lebanon Tel: +961 1 615300x3030; fax: +961 1 325382; e-mail: habib.rizk@usj.edu.lb, habibrizk84@hotmail.com Current Opinion in Otolaryngology & Head and Neck Surgery 2011, 19:000–000 Purpose of review This review is set to revisit the pathogenesis of aspirin-exacerbated respiratory disease (AERD), the diagnostic method used, and finally the real impact of aspirin desensitization on chronic sinusitis with nasal polyposis (CRSwNP) in aspirin intolerant patients. Recent findings In AERD, increased baseline production of cysteinyl-leukotriene (Cys-LT) is associated with upregulation of Cys-LT receptors on nasal inflammatory cells. This is further aggravated by inhibition of cyclooxygenase-1 by aspirin and other NSAIDs. New-found genetic markers need further study. Oral aspirin challenge is still the gold standard of diagnosis and can be safely conducted in a specialized outpatient clinic. Oral and endonasal aspirin desensitization show positive impact on CRSwNP course with decreased polyp recurrence, decreased number of hospitalizations, and decreased need for corticosteroids. Modulation of arachidonic acid metabolism and inhibition of intracellular biochemical pathways in key inflammatory cells involving anti-inflammatory cytokines interleukin (IL)-4 and IL-13 explain the clinical outcomes. Summary Future studies should focus on establishing the lowest possible dose to maintain disease under check, allowing more widespread use of this underutilized and underrecognized treatment modality. Keywords aspirin desensitization, aspirin-exacerbated respiratory disease, chronic rhinosinusitis with nasal polyposis, cysteinyl-leukotrienes Curr Opin Otolaryngol Head Neck Surg 19:000–000 ß 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins 1068-9508 1068-9508 ß 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins DOI:10.1097/MOO.0b013e3283450102