Macrocephaly in an 8-month-old infant.

An 8-month-old infant presents with macrocephaly and a mild motoric deficit. The pediatrician asks a complementary MR examination to exclude hydrocephalus. MR-images show diffuse swelling of white matter with preservation of the corpus callosum and the internal capsule. Also the occipital periventricular and subcortical white matter is better preserved than the rest of the cerebral white matter (A, axial T2 weighted image). The cerebellum seems normal (B, coronal T2 weighted image). The anterior temporal white matter is rarified (C, sagittal T1 weighted image, arrow). Axial T2 FLAIR image (D, arrow) shows a lower signal intensity in the anterior temporal subcortical white matter than in the cortex. Diagnosis of van der Knaap’s disease or MLC (megalencephalic leukencephalopathy with subcortical cysts) was made.