FIBROSING MEDIASTINITIS AND RHEUMATOID ARTHRITIS: AN AUTOIMMUNE INFLAMMATORY CONNECTION

Abstract

SESSION TITLE: Disorders of the Mediastinum 2 SESSION TYPE: Fellow Case Reports PRESENTED ON: 10/10/2018 10:45 am - 11:45 am INTRODUCTION: Fibrosing mediastinitis (FM) is a rare condition characterized by an aggressive fibrotic reaction in the mediastinum. In the United States, the disorder is most commonly seen in patients with a prior infection with Histoplasma capsulatum, presumably due to an excessive immune response. This immune response has been associated with IgG4 and autoimmune disorders. We present a case of a patient with post-infectious FM who subsequently developed seropositive rheumatoid arthritis. CASE PRESENTATION:A 53-year-old gentleman with asthma and recurrent pneumonia presented to our hospital with worsening dyspnea and wheezing. Computed tomography (CT) scan of the chest demonstrated extensive calcified mediastinal lymph nodes with soft tissue encasement of multiple central and segmental bronchi (Image 1 and 2). Additionally, calcified granulomas were noted in the right middle and lingular lobes as well as the liver and spleen. Findings were consistent with a radiographic diagnosis of post-infectious FM. However, infectious workup was negative, including Histoplasma antigen and antibody. Autoimmune workup was also unrevealing. Transbronchial biopsy demonstrated reactive pneumocytes with chronic inflammation and scattered areas of fibrosis. The patient was started on high dose steroids with initial improvement in symptoms; however, he relapsed once tapered off steroids. Two years after the initial presentation, the patient was hospitalized with joint pain and swelling in his hands and right shoulder along with dyspnea and pleuritic chest pain. Cyclic citrullinated peptide antibodies were strongly positive at this time. Rheumatoid arthritis (RA) was diagnosed and controlled with steroids. Progressive pulmonary symptoms prompted rituximab therapy with some stabilization of his disease. DISCUSSION: There is growing evidence that FM is an immune-mediated disorder, yet the etiology remains unknown. A histopathological similarity between FM and IgG4-related disease has been observed, and other autoimmune conditions are associated with FM (1,2). These findings suggest a common pathogenesis or pathway of chronic inflammation. Autoimmune antibodies in RA can activate IgG4, which may perpetuate inflammation by complement activation (3). Immune-targeted therapies likely have a role in the treatment of FM. Patients with FM should be screened for systemic autoimmune disease at diagnosis although new conditions may develop over the course of time as seen in our patient. CONCLUSIONS: We present the unique case of a patient with FM who subsequently developed a systemic autoimmune disease. An association between RA and FM has not been previously reported in the literature. These diseases may share a common pathway of immune-mediated inflammation. Reference #1: Peikert, T et al. Histopathologic Overlap between Fibrosing Mediastinitis and IgG4-Related Disease. International Journal of Rheumatology 2012 2012:1-7 Reference #2: Rossi, GM et al. Idiopathic Mediastinal Fibrosis: a Systemic Immune-Mediated Disorder. A Case Series and a Review of the Literature. Clinic Rev Allerg Immunol 2017;52:446-459 Reference #3: van de Stadt, LA et al. Antibodies to IgG4 Hinge Can Be Found in Rheumatoid Arthritis Patients During All Stages of Disease and May Exacerbate Chronic Antibody-Mediated Inflammation. Arthritis & Rheumatology 2014,66:1133–1140 DISCLOSURES: No relevant relationships by Timothy Hotze, source=Web Response No relevant relationships by Anthony McClafferty, source=Web Response no disclosure on file for Purvesh Patel