Aim: Asymptomatic visceral artery aneurysms (VAAs) have increasingly been found, with most being either atherosclerotic VAAs or fibromuscular dysplasia (FMD)-associated VAAs. However, little is known about the pathogenesis of both diseases. We aimed to identify the differences in the distribution pattern of lipid molecules between atherosclerotic VAAs and FMD-associated VAAs.
Methods: We conducted a histological study of VAAs using imaging mass spectrometry (IMS) to assess the accumulation of lipid molecules in both the aneurysmal sac and the adjacent arteries without aneurysmal changes in 17 VAA samples, which were resected during the surgery.
Results: IMS revealed characteristic distributions of cholesterol ester in intima and media in the atherosclerotic VAAs, which was hardly detected in FMD-associated VAAs. However, lysophosphatidylcholine (lysoPC), a proinflammatory and proapoptotic lipid mediator, was accumulated in the medial ridge of the adventitia of FMD-associated in the aneurysmal sac, and it was also diffusely accumulated in the adjacent arteries. In contrast, lysoPC was accumulated in the area of intimal hyperplasia in atherosclerotic VAAs and the adjacent arteries.
Conclusion: The distribution patterns of lipid molecules were different between the FMD-associated and atherosclerotic VAAs. The diffuse accumulation of lysoPCs in the visceral arteries may be a predisposition for the formation of FMD-associated VAAs.