Clinical characteristics of sitosterolemic children with xanthomas as the first manifestation
Background: Sitosterolemia (STSL) is an extremely rare genetic disease. Xanthomas as the first symptom is frequently misinterpreted as familial hypercholesterolemia (FH) in children. Inappropriate treatment may deteriorate the condition.  Objectives: The goal of this study was to summarize the clinical characteristics of children with STSL who had xanthomas as their first symptom and to provide clues for early clinical diagnosis.  Methods: We summarized the clinical characteristics of STSL patients, and investigated the differences between the STSL and FH groups, as well as the diagnostic value of STSL. Results: Two tertiary pediatric endocrinology departments contributed ten STSL cases. Five of the patients (50%) experienced mild anemia, whereas two (20%) had vascular complications. The xanthomas displayed comparable morphologies to the FH group. There were ten cases of homozygous FH with xanthomas as the predominant symptom, but no anemic patients. While serum cholesterol (Chol) and low density lipoprotein cholesterol (LDL-c) levels were significantly higher (p values of 0.002 and 0.003, respectively), MPV levels and anemia proportions were significantly lower (the p values were 0.009 and 0.033, respectively) than in the STSL group. The AUC values of Chol, LDL-c, MPV, and anemia for the diagnosis of STSL were 0.910, 0.890, 0.869, and 0.750, respectively. Chol15.41 mmol/L, LDL-c13.22 mmol/L, MPV9.05 fl, or anemia present were the best thresholds for diagnosing STSL. Conclusions: The morphologies of STSL xanthomas vary. When xanthomas were the initial symptom of a child with Chol15.41 mmol/L, LDL-c13.22 mmol/L, MPV9.05 fl, or anemia, the clinical diagnosis of STSL was most likely made.