Immunoglobulin G4-related disease (IgG4-RD) is a systemic immune-mediated disease characterized by inflammation, fibrosis, and mass-forming lesions that can occur in nearly any organ system. Common manifestations include enlargement of the lacrimal and major salivary glands, various forms of pulmonary disease, autoimmune pancreatitis, sclerosing cholangitis, tubulointerstitial nephritis, and retroperitoneal fibrosis. The diagnosis of IgG4-RD requires clinicians to recognize typical sites of IgG4-RD involvement and to synthesize data from the disease's clinical, radiological, laboratory, and pathological manifestations [1,2].

Vascular inflammation is common in IgG4-RD and can contribute to substantial morbidity and even mortality. The most commonly described histopathologic manifestation of the vascular disease in IgG4-RD is obliterative phlebitis, a microscopic finding that is recognized widely as a pathologic hallmark of this condition [3]. Although obliterative phlebitis is observed frequently in organs involved by IgG4-RD, clinical features of small-vessel vasculitis—which typically present as cutaneous leukocytoclastic vasculitis—are less common but reported [4], [5], [6]. The ability of IgG4-RD to affect the aorta is also well-known [7], [8], [9], [10].

Between these extremes—the involvement of small vessels in the form of obliterative phlebitis that is detected only microscopically and the involvement of the aorta—IgG4-RD affecting medium-sized arteries is poorly described. A medium-vessel vasculitis is defined as inflammatory vascular disease affecting and damaging the walls of blood vessels that have penetrated a viscus [11].

Coronary artery involvement (CAI), a form of medium-vessel arteritis with potentially lethal consequences in IgG4-RD, has been described in case reports and small case series [7,8,[12], [13], [14], [15], [16], [17]]. We identified 13 patients with IgG4-RD involving the coronary arteries from our single-center cohort and report data on the patients’ demographics, disease characteristics, radiologic patterns of disease, and clinical consequences here.