Systemic Fibroinflammatory Disorders - Diffuse (Thoraco-Abdominal) Periaortitis

Chronic periaortitis (CP) is usually referred to as a spectrum of rare diseases characterized by the presence of an aberrant fibroinflammatory tissue usually located around the infrarenal portion of the abdominal aorta and around the iliac arteries [1]. A recent study showed that in approximately one third of cases CP may also involve other vascular districts, particularly the thoracic aorta and its major branches, which reinforces the view that CP may be a systemic fibroinflammatory disease [2]. A systemic immune-mediated etiopathogenesis of diffuse CP that has replaced the classical theory according to which CP was due to a localized inflammatory response to aortic atherosclerosis plaque antigens; the “systemic immunemediated” theory is also supported by other findings including the association with other autoimmune diseases and with HLA-DRB1*03 and the presence of systemic clinical manifestations [3–5]. Another important element which may support the autoimmune etiology comes from the histological examination of CP biopsies, given that the pattern of vascular and perivascular inflammation in CP is consistent with an inflammatory vascular disease: as in giant cell arteritis (GCA) and Takayasu arteritis (TA), inflammation in CP predominates in the adventitia where the vasa vasorum, a possible port of entry for disease-triggering pathogens, are often inflamed [3, 6]. In some cases, diffuse CP could be included in the spectrum of IgG4-related disease (IgG4-RD) due to immunohistochemistry revealing the presence of IgG4- positive plasma cell infiltration [7] and/or in cases of serum IgG4 elevation.