FRI087 Tuberous Xanthomas And Thrombocytopenia In A Patient With A New Diagnosis Of Sitosterolemia

Disclosure: S. Grigoryan: None. T. Else: None. Introduction/ Background: Sitosterolemia is a rare autosomal recessive disorder characterized by increased plasma sterol levels, that can lead to xanthomas, premature atherosclerosis, and hematologic abnormalities. It is most commonly caused by pathogenic variants in either ABCG5 or ABCG8 encoding sterol transporters that excrete sterols, leading to increased intestinal absorption and decreased biliary excretion of plan sterols. While patients with sitosterolemia have elevated LDL cholesterol levels, the pathophysiology of this process is still unclear. Clinical Case: A 46-year-old man presented with tuberous xanthomas and hyperlipidemia (HLD). In the past surgical removal had been attempted, but the lesions recurred. Prior labs: total cholesterol level was 235 mg/dL, triglycerides 85 mg/dL, HDL 61 mg/dL, LDL 157 mg/dL and mild thrombocytopenia (88 -127 K/uL) with giant platelets and anemia. Prior to the initial visit he started 40 mg atorvastatin with a subsequent increase to 80 mg daily. Physical exam was notable for periocular xanthelasmas and tuberous xanthomas. Achilles tendons appeared thickened without nodules. There was no family history of premature cardiac disease. Initial labs: Total cholesterol was 206 mg/dL(ref 120-200 mg/dL), TG mg/dL 66 mg/dl (ref 40-200mg/dL), LDL 119 mg/dL (ref 70-130 mg/dL), HDL 62 mg/dL (ref >40), platelets 111 K/uL (ref 150-400 K/uL) with 27.7% immature fraction, Hb 13.6 g/dL (13.5-17 g/dL). Plasma sterols were significantly elevated, campesterol 182.2 mg/L (ref <8mg/L), cholestanol 20.6 mg/L (ref <6 mg/L ), sitosterol 247.2 mg/L (ref <15mg/L ), stigmasterol 11.5 mg/L (ref <0.5 mg/L), indicative of a diagnosis of sitosterolemia. Coronary artery calcification (CAC) revealed a score of 15 which represents 50-75th percentile for age and gender, indicating CAD disease in the patient. Following the diagnosis of sitosterolemia, the patient started ezetimibe 10 mg daily, atorvastatin was decreased to 40 mg daily given the success at decreasing the LDL. Follow up LDL decreased to 58 mg/dL (48% decrease) and non-HLD to 71 mg/dL (53% decrease). Patient was counseled on dietary modification with a focus on avoidance of plant-based oils as well as referred to medical genetics and a dietician for more in-depth counseling. Genetic confirmation is pending. Conclusion: The global prevalence is estimated to be 1/1,000,000∼5,000,000. However, prevalence is likely underestimated due to the significant clinical and biochemical overlap with other hyperlipidemias and great variations in phenotype. Due to the differences in treatment and dietary counseling, it is important to consider this diagnosis, particularly in patients with typical concurrent hematological abnormalities. Presentation: Friday, June 16, 2023