The Importance of Ophthalmic Examination in Initial Diagnostic Process of Xanthoma: Two Case Reports and Literature Review of Cerebrotendinous Xanthomatosis

Background: Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive disease where deficiency of sterol 27-hydroxylase leads to reduced production of CDCA. In such cases, life expectancy is only 4–6 decades, with progressive neurologic dysfunction such as dementia and spinal cord paresis, unless the condition is diagnosed early and treated appropriately. Herein, we aim to raise awareness regarding the importance of ophthalmic examination in evaluating of xanthoma. Clinical Cases: Case 1: In a 58-year-old man with no neurological symptoms; bilateral cataracts were detected during the initial diagnostic process. This patient had two siblings with xanthoma; one died from cerebral infarction and the other from biliary tract cancer. Another sibling had premature acute cardiovascular disease without xanthomas. Baseline lipid profiles were nearly within the normal range, while lipoprotein A was approximately 2.5 times higher than the normal. CTX was confirmed by the detection of a homozygous mutation in the CYP27A1 gene and high plasma cholestanol level (8.5 mg/L; reference range 0.0–5.0 mg/L). He has been taking oral CDCA (250 mg, three times daily). Case 2: In a 24-year-old man with no neurological symptoms or intellectual disability, premature bilateral cataracts were detected 1 year prior to diagnosis of CTX. None of his family members had xanthoma or premature cardiovascular disease. Lipid profile showed a similar pattern to that of Case 1; CTX was confirmed by the detection of a homozygous mutation in the CYP27A1 gene and high plasma cholestanol level (21.33 mg/L). One year after starting CDCA (250 mg, three times daily), cholestanol levels dropped to 7.34 mg/L. They were measured annually and identified as 5.08 mg/L, 4.2 mg/L, 4.7 mg/L, and 3.8 mg/L at 24, 38, 61, and 72 months, respectively. It took approximately 2 years for the normalization of his cholestanol level. There were no recurrences of xanthoma or progression of complications in target organs after 6 years of treatment. Conclusion: Early diagnosis improves the outcomes of CTX, allowing proper treatment. Bilateral cataracts caused by cholestanol buildup on the crystalline lens due to CTX usually occur within the first three decades of life. This manifestation does not occur in patients with xanthoma, familial hypercholesterolemia, or sitosterolemia. Taken together, this report suggests that premature bilateral cataracts are a specific marker that can accelerate early diagnosis of CTX. References: (1) Duell PB et al. Diagnosis, Treatment and Clinical Outcomes in 43 Cases with CTX. Journal of Clinical Lipidology. 2018;12:1169 (2) Salen G, Steiner RD. Epidemiology, diagnosis, and treatment of CTX. J Inherit Metab Dis 2017: 40:771