Incidental detection of IgG4-related coronary periarteritis on coronary calcium scoring

A 59-year-old asymptomatic man underwent non-contrast computed tomography (CT) coronary calcium scoring, which revealed a markedly elevated Agatston score of 1046. Although such scores usually indicate advanced atherosclerosis, careful inspection of the non-contrast images demonstrated abnormal expansion of the vessel contour beyond the calcified intima (Panel A, arrow). Subsequent coronary CT angiography revealed a circumferential periarterial soft-tissue cuff encasing the calcified lumen, creating a characteristic ‘pigs-in-a-blanket’–like appearance (Panel B, arrow), raising suspicion of coronary periarteritis.1, 2 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET)/CT demonstrated increased metabolic activity along the periarterial soft tissue of all three major coronary arteries, most pronounced in the left anterior descending artery (SUVmax 4.2, arrow), as well as the infra-renal aorta, accompanied by FDG-avid mediastinal and hilar lymphadenopathy (Panel C, arrowheads), consistent with active systemic inflammatory involvement. Serum IgG4 level was markedly elevated at 1590 mg/dL, supporting the diagnosis of IgG4-related coronary periarteritis. Recently, Kawaguchi et al. reported a fatal presentation of IgG4-related periarteritis manifesting as out-of-hospital cardiac arrest.3 In contrast, the present case illustrates that this potentially life-threatening condition may be detected at a subclinical stage through careful evaluation of routine coronary calcium scans. Careful inspection of the vessel caliber beyond coronary calcification is essential, as apparent ‘wall thickening’ on non-contrast CT may represent the earliest imaging clue of active coronary periarteritis, allowing timely diagnosis before catastrophic cardiovascular events.