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Comment & Response
August 2018

Metachromatic Leukodystrophy: Too Frequent (Mis)Diagnosis?—Reply

Author Affiliations
  • 1Department of Neurology, Peking University Third Hospital, Beijing, China
JAMA Neurol. 2018;75(8):1027-1028. doi:10.1001/jamaneurol.2018.1518

In Reply We thank Politi et al for their interest in our article.1 Politi and colleagues point out that it is confounding to emphasize metachromatic leukodystrophy (MLD) in the differential diagnosis because it could have been ruled out much sooner from the brain magnetic resonance imaging (MRI) and the level of arylsulfatase A (ARSA) activity.

First, we agree that the demyelinating process of adult MLD usually starts in the frontal white matter and extends to more posterior white matter structures over time. However, in late-infantile MLD, the lesions usually start in the occipital white matter and are more prominent in the occipital lobes than the frontal lobes.2 The cause of the different demyelinating patterns between adult and late-infantile MLD is not well clarified. Although the tigroid pattern is a typical sign of MLD, it presented in about 50% of patients with MLD in a study including 28 patients with MLD.3 Meanwhile, the brain MRI scans of some patients with MLD are atypical or even without white matter lesions.4 Singh et al4 described a patient with late-infantile MLD without white matter involvement on brain MRI. In our case report,1 the serial brain MRI scans show a spreading from occipital white matter lesions to confluent white matter lesions in the bilateral centrum semiovale and periventricular areas. Although it is not typical for patients with adult MLD, we think that the diagnosis of MLD cannot be excluded, considering the heterogeneity of imaging manifestations in patients with MLD. Other clinical data should be considered together for final diagnosis.

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