Inflammatory ascending aortic disease: perspectives from pathology

Inflammatory diseases of the aorta comprise a spectrum of disease with diverse clinical and histopathologic presentations. Broadly, they may be dichotomized into infectious and noninfectious varieties. Although uncommon, infectious forms, caused by bacteria, fungi, or mycobacteria, may result from hematogenous seeding of the aorta or direct spread from a contiguous infectious source. The noninfectious forms include a number of entities, the most common of which is atherosclerosis, a disease that primarily affects the aortic intima but has important secondary effects on the media and adventitia that may result in aneurysm formation. Other important noninfectious inflammatory diseases include giant cell arteritis, Takayasu arteritis, granulomatosis with polyangiitis (Wegener granulomatosis), sarcoidosis, and lymphoplasmacytic aortitis. Importantly, there is increasing recognition that there is a subset of cases of lymphoplasmacytic aortitis perhaps better classified under the spectrum of so-called IgG4-related sclerosing disease, with important clinical and therapeutic ramifications. This review focuses on the variable and defining characteristics of the inflammatory aortopathies, specifically those affecting the ascending aorta, and discusses areas of important clinical and pathological distinction between them.