Immunoglobulin G4-related disease: some missing pieces in a still unsolved complex puzzle

IgG4-related disease: a clinical perspective

IgG4-related disease (IgG4-RD) is a recently recognized fibro-inflammatory disorder that can affect almost any organ. Common presentations include major salivary and lacrimal gland enlargement, orbital disease, autoimmune pancreatitis, retroperitoneal fibrosis and tubulointerstitial nephritis. The main histopathological features are a dense, polyclonal, lymphoplasmacytic infiltrate rich in IgG4+ plasma cells, storiform fibrosis and obliterative phlebitis. The precise pathogenic mechanisms of IgG4-RD are still unclear. CD4+ T and B cells, including IgG4-expressing plasmablasts, constitute the major inflammatory cell populations and are believed to cause organ damage and tissue fibrosis. The diagnosis of the disease may be challenging and should be based on specific histopathological findings, typical laboratory and radiological aspects and an appropriate clinical context. The first-line treatment of IgG4-RD is based on glucocorticoids, which are usually efficacious. However, B cell depletion induced by rituximab has also been found to induce remission in steroid-resistant disease or has been used as steroid-sparing agent for relapsing disease. This review provides an update on clinical and therapeutic aspects of IgG4-RD.

Aortitis and periaortitis: The puzzling spectrum of inflammatory aortic diseases

Aortitis and periaortitis are inflammatory diseases of the aorta and its main branches; they differ in the extension of inflammation, which is confined to the aortic wall in aortitis, and spreads to the periaortic space in periaortitis. Aortitis is classified as non-infectious or infectious. Non-infectious aortitis represents a common feature of large-vessel vasculitides but can also be isolated or associated with other rheumatologic conditions. Periaortitis can be idiopathic or secondary to a wide array of etiologies such as drugs, infections, malignancies, and other proliferative diseases. Notably, both aortitis and periaortitis may arise in the context of IgG4-related disease, a recently characterised fibro-inflammatory systemic disease. Prompt recognition, correct diagnosis and appropriate treatment are essential in order to avoid life-threatening complications.

Clinically isolated aortitis: pitfalls, progress, and possibilities

Non-infectious aortitis may be caused by several distinct systemic rheumatologic diseases. In some patients, aortitis is identified either pathologically or radiologically in the absence of clinical evidence of a systemic vasculitis. By consensus nomenclature, such cases are referred to as clinically isolated aortitis (CIA). Some systemic disorders may initially present as CIA including giant cell arteritis (GCA), IgG4-related disease, infectious aortitis, and granulomatosis with polyangiitis. CIA most commonly occurs in women of European descent over the age of 50 and, thus, mirrors the gender, age, and geographic distribution of GCA. CIA most often demonstrates a granulomatous/giant cell pattern of inflammation (GPI), and CIA-GPI is pathologically indistinguishable from aortitis due to GCA. In many cases, CIA may be a manifestation of extracranial GCA. CIA is being identified both pathologically in resected aortic tissue and radiologically by computed tomography scanning, magnetic resonance imaging, and fluorodeoxyglucose positron emission tomography. However, there appears to be significant differences between pathologically defined CIA and radiologically defined CIA. Multiple studies have shown that patients with CIA are at increased risk for subsequent aortic events (new aneurysms or dissections) and thus it is recommended to monitor these patients with periodic aortic imaging. While the data is currently limited, there is increasing evidence that at least some patients with CIA may benefit from immunosuppressive therapy.

Vascular diseases: aortitis, aortic aneurysms, and vascular calcification

Inflammatory diseases of the aorta broadly include noninfectious and infectious aortitis, periaortitis, atherosclerosis, and inflammatory atherosclerotic aneurysms. Aortitis is uncommon but is increasingly recognized as an important cause of aortic aneurysms and dissections. Abdominal (AAA) and thoracic aortic aneurysms (TAA) have different pathologies and etiologies. AAAs are the most common type of aortic aneurysm, and the vast majority of these are atherosclerotic. The causes of TAA vary depending on the site of involvement, but medial degeneration is a common pathologic substrate, regardless of etiology, and genetic influences play a prominent role in TAA expression. Standardized classification schemes for inflammatory and degenerative diseases of the aorta have only recently been added to the pathology literature. A brief overview of the new histopathologic classifications for aortic inflammatory and degenerative diseases has recently been published by the Society for Cardiovascular Pathology and the Association for European Cardiovascular Pathology as a consensus document on the surgical pathology of the aorta. Vascular calcification is a highly regulated biologic process, and the mechanisms leading to vascular calcification are under investigation. Calcification may occur in the intima (atherosclerotic) or in the media secondary to metabolic disease. Rarely, vascular calcification may be associated with genetic disorders.