IgG4-Related Disease Presenting With Diffuse Coronary Atherosclerosis Characterized by Marked Lipid-Rich Necrotic Core Burden

BACKGROUND: IgG4-related disease (IgG4-RD) is a systemic fibroinflammatory disorder with multiorgan involvement, including increasingly recognized cardiovascular manifestations such as aortitis and periarteritis. Coronary involvement remains rare and is often clinically silent and poorly characterized, with most reported cases associated with pericoronary inflammation, ectasia, or aneurysmal dilation rather than diffuse high-risk atherosclerosis. CASE SUMMARY: A 63-year-old man with longstanding IgG4-RD presented with abdominal pain and no cardiac symptoms. Computed tomography demonstrated periaortic inflammation, incidental coronary calcification, and markedly elevated serum IgG4. Coronary computed tomography angiography revealed diffuse pericoronary thickening without aneurysmal dilation. Advanced plaque analysis showed an extreme coronary plaque burden dominated by lipid-rich necrotic core and noncalcified plaque, consistent with high-risk atherosclerosis. DISCUSSION: This case expands the spectrum of IgG4-related coronary involvement, demonstrating diffuse, severe, inflammation-associated atherosclerosis without ectasia or aneurysm and highlighting the disconnect between symptoms and disease burden, with potential for silent, high-risk coronary disease. TAKE-HOME MESSAGE: IgG4-RD may harbor clinically silent but high-risk coronary disease, supporting vigilance, proactive coronary imaging, aggressive immunosuppression, and intensive secondary prevention.