title: Hypersensitivity pneumonitis associated with azathioprine therapy in a patient with granulomatosis with polyangiitis.
abstract: Granulomatosis with polyangiitis (GPA), an autoimmune disease characterized by inflammatory granulomas and necrotizing small-vessel vasculitis, primarily affects the respiratory tract and kidneys. Azathioprine (AZA) is a purine analog that is commonly used for maintaining GPA remission after induction therapy with cyclophosphamide. While the dose-dependent side effects of AZA are common and well known, hypersensitivity reactions such as pulmonary toxicity are rare. Here, we describe a case involving a 38-year-old man with GPA-associated pauci-immune crescentic glomerulonephritis who developed subacute hypersensitivity pneumonitis (HP) during AZA maintenance therapy. Five months after the initiation of AZA administration (100 mg/day), the patient was admitted with a 7-day history of cough, dyspnea, and fever. High-resolution computed tomography of the chest showed ill-defined centrilobular nodules and diffuse ground-glass opacities in both lung fields. Bronchoscopy with bronchoalveolar lavage was negative for infectious etiologies. A transbronchial lung biopsy specimen revealed poorly formed non-necrotizing granulomas. A chest radiograph obtained at 2 weeks after discontinuation of AZA showed normal findings. The findings from this case suggest that AZA-induced HP should be considered as a differential diagnosis when a patient with GPA exhibits fresh pulmonary lesions accompanied by respiratory symptoms during AZA therapy.
authors.affiliation: Division of Nephrology, Department of Internal Medicine, Catholic University of Daegu School of Medicine, 17-Gil 33, Duryugongwon-ro, Nam-gu, Daegu, 42472, Korea. ihlee@cu.ac.kr.
authors.forename: In Hee
authors.initials: IH
authors.lastname: Lee
authors.affiliation: Division of Nephrology, Department of Internal Medicine, Catholic University of Daegu School of Medicine, 17-Gil 33, Duryugongwon-ro, Nam-gu, Daegu, 42472, Korea.
authors.forename: Gun Woo
authors.initials: GW
authors.lastname: Kang
authors.affiliation: Division of Pulmonary and Critical Medicine, Department of Internal Medicine, Catholic University of Daegu School of Medicine, Daegu, Korea.
authors.forename: Kyung Chan
authors.initials: KC
authors.lastname: Kim
mesh_terms: D000328:Adult; D000542:Alveolitis, Extrinsic Allergic / Q000139:chemically induced* / Q000175:diagnosis / Q000276:immunology; D001379:Azathioprine / Q000009:adverse effects*; D001706:Biopsy; D001999:Bronchoscopy; D004342:Drug Hypersensitivity / Q000175:diagnosis / Q000209:etiology* / Q000276:immunology; D014890:Granulomatosis with Polyangiitis / Q000175:diagnosis / Q000188:drug therapy*; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage*; D008297:Male; D011237:Predictive Value of Tests; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D007166:Immunosuppressive Agents; D001379:Azathioprine
keywords: Azathioprine; Granulomatosis with polyangiitis; Hypersensitivity pneumonitis; Wegener’s granulomatosis