Diagnostic challenge: A case of late-onset spinal form cerebrotendinous xanthomatosis

A 42-year-old woman was admitted with lower extremity weakness slowly progressing over 10 years. Examination showed spastic paraparesis, deep sensory deficit on legs, and mild intentional tremor of hands. Extensive serum and CSF analyses were unremarkable. Bilateral symmetrical internal capsule, crus cerebri, and longitudinal spinal cord lesions and particularly slight involvement of dentate nuclei on MRI (figure), together with history of parental consanguinity, suggested spinal form of cerebrotendinous xanthomatosis, despite absence of all cardinal systemic features, including xanthomas.1 Diagnosis was revealed by high plasma cholestanol level (15 µg/mL, normal range 0.45–3.75) and novel homozygous mutation (p.L524R [c.1571T > G]) on CYP27A1 gene by DNA sequencing. Chenodeoxycholic acid treatment was started.