A CASE OF IGG4-RELATED INTERSTITIAL LUNG DISEASE MANIFESTING AS RECURRENT NECROTIZING PNEUMONIA

Abstract

SESSION TITLE: Medical Student/Resident Lung Pathology SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: IgG4-related disease is a newly recognized fibroinflammatory disorder characterized by enlargement of one or more organs with classic histopathologic findings of diffuse lymphoplasmacytic infiltration and IgG4+ plasma cells. Presentation relies on the primary organ affected. Pulmonary disease can be especially difficult to characterize, as its course may mimic various lung pathologies. In this case report, we describe a case of IgG4-related interstitial lung disease (ILD) that manifested as recurrent necrotizing pneumonia. CASE PRESENTATION: A 33-year old female with past medical history of recent Group B Streptococcal bacteremia with aortic valve endocarditis was admitted for severe aortic insufficiency, necessitating aortic valve replacement. She developed hypoxic respiratory failure requiring ventilation support and treatment for pneumonia. After discharge, she was soon readmitted for right sided necrotizing pneumonia. Initial bronchoscopy positive for Streptococcus Viridians and Lactobacillus with repeat bronchoscopy after antibiotics showing normal flora. Patient was ultimately readmitted for left sided chest pain and hypoxia. Initial workup showed elevated inflammatory markers and CT chest with right-sided, multifocal pneumonia with cavitations. Microbiology and immunologic studies unremarkable. The patient did not improve on 1 month of antibiotics so underwent a lung biopsy revealing for interstitial fibrosis, inflammatory lymphoplasmacytic infiltrate, and positive IgG4 staining with elevated serum IgG4 levels- diagnostic for IgG4-related ILD. The patient was started on PO prednisone with complete resolution on most recent follow-up 2 months later. DISCUSSION: IgG4-related disease was first recognized in 2003 and is now understood as a spectrum of related diseases. In particular, the prevalence of pulmonary involvement remains uncertain, and neither diagnostic criteria nor treatment have officially been established. Review of previous cases reveals diverse presentations sharing features of other lung pathologies including pneumonias, cancer, and granulomatous diseases. The current report describes IgG4-related ILD manifesting as recurrent necrotizing pneumonia confirmed via characteristic lung pathology and an elevated serum IgG4 level of 235 mg/dL. Treatment relied on previous cases describing good prognosis from corticosteroids; specifically, prednisone 0.6 mg/kg with plans for slow taper. Patient was successfully weaned from oxygen support without further addition of DMARDs. CONCLUSIONS: IgG4-related disease encompasses a spectrum of fibroinflammatory disorders that can affect multiple organ systems, including the lungs. Given the evolving nature of IgG4-related ILD, diagnosis can be especially difficult given the multitude of presentations mimicking other infectious, neoplastic, and inflammatory disease processes. Larger studies could further understanding of this complex disease. Reference #1: Stone, John H., et al. “Mechanisms of Disease: IgG4-Related Disease.” The New England Journal of Medicine, 9 Feb. 2012. Reference #2: Chen, Chiu-Fan et al. “IgG4-related lung disease presenting as interstitial lung disease with bronchiolitis: A case report.” Medicine vol. 96,49 (2017): e9140. doi:10.1097/MD.0000000000009140 Reference #3: Umehara, Hisanori, et al. “Comprehensive diagnostic criteria for IgG4-related disease (IgG4-RD).” Modern Rheumatology, vol. 22, no. 1, 2 Jan. 2014, pp. 21-30. Abstract. DISCLOSURES: no disclosure on file for Duc Ho; No relevant relationships by Larry Jankelowitz, source=Web Response No relevant relationships by Ramier Lehne, source=Web Response