Metachromatic Leukodystrophy: Too Frequent (Mis)Diagnosis

Recently, Wu et al1 reported the case of an adult patient with late-onset cobalamin C disease who received an incorrect diagnosis of adult metachromatic leukodystrophy (MLD). In this patient, the disease onset was characterized by acute psychiatric symptoms and spastic paraparesis. A brain magnetic resonance imagining (MRI) scan performed 2 months after the onset showed an area of hyperintensity on fluid-attenuated inversion recovery images in the right occipital subcortical white matter. The involvement of bilateral occipital white matter and centrum semiovale was evident at a follow-up MRI that was performed 21 months after the onset. At this time, arylsulfatase A (ARSA) enzyme activity was tested in peripheral blood leukocytes, and the results showed that the levels were half of the normal lower limit. Metachromatic leukodystrophy was suspected and the patient underwent genetic testing. This is an interesting case, but in our opinion, it is confounding to emphasize MLD in the differential diagnosis because it could have been ruled out much sooner