IGG4 Aortopathy: An Underappreciated Cause of Non-Infectious Thoracic Aortic Aneurysm

Abstract

Introduction: IgG4 related disease is a fibro-inflammatory disorder of unknown aetiology, which has an array of clinical presentations depending on specific tissue or organ involvement. Since 2008, non-infectious thoracic aortitis has been recognised as another possible manifestation of IgG4-RD. It is however, often unrecognised and under investigated, causing acute syndromes such as acute aortic dissection. Case report: We report the case of a 57-yr-old female marathon runner who underwent a valve spearing aortic root replacement (David's procedure) for what it was initially thought to be a dilated aortic root and ascending aortic aneurysm. Intraoperatively, acute dissection was recognised with the presence of an adventitial haematoma and a tear in the intima close to the sinotubular junction. Histopathology confirmed the presence of active mural inflammation with microabscess formation and positive IgG4 immunohistochemistry following an extensive investigation of an infectious cause. Her recovery was unremarkable and she was referred and followed by the Immunology department. Discussion: Immunoglobulin G4-related thoracic aortitis is a rare phenomenon. Few population based studies of IgG4-RD have been performed and the epidemiology of the disease remains poorly described. IgG4-RD is a fibro-inflammatory disorder of unknown aetiology and has a multiplicity of clinical manifestations owing to its ability to infiltrate any organs or tissues. Particular features which lend to the diagnosis being made include: storiform fibrosis, dense lymphoplasmatic infiltrate with increased IgG4 plasma cell concentration and/or increased IgG4/IgG ratio, and obliterative phlebitis. In our case, the immunohistochemistry for IgG4 was positive with absence of an infectious organism. Conclusion: 1.This case represents another presentation of IgG4 related thoracic aortitis with acute dissection. 2. Our report demonstrates the difficulties in diagnosing IgG4-RD. 3.This new disease entity is poorly understood and the subtleties of this case exhibit the need for a review of the diagnostic criteria.