Beyond cholesterol: regression of carotid plaques in an adolescent-a case report.

BACKGROUND: Sitosterolaemia is a rare lipid disorder characterized by massive accumulation of phytosterols. Due to its non-specific clinical features and the lack of routine sterol quantification, diagnostic delays are common, leading to inappropriate dietary interventions that may paradoxically accelerate vascular damage. CASE SUMMARY: We herein describe the case of a 13-year-old boy with sitosterolaemia and early-onset atherosclerosis against a background of a 7-year diagnostic delay. Following the identification of a paradoxical pro-atherogenic effect of a standard lipid-lowering diet, treatment with a plant-oil-restricted diet and cholestyramine resulted in a 51.7% reduction in carotid plaque thickness. DISCUSSION: This case highlights the necessity of screening for sitosterolaemia in paediatric patients with unexplained carotid plaque. Plaque resolution was achieved only after replacing conventional lipid-lowering strategies with targeted phytosterol-lowering interventions and specialized dietary modifications.