Disappearance of a white matter lesion in incontinentia pigmenti.

We report a 12-month-old Japanese female with incontinentia pigmenti, in whom magnetic resonance imaging (MRI) disclosed a small transient lesion in the white matter. After birth, she developed some vesicular skin eruptions that mainly involved the lower extremities. These skin lesions increased in size and number and became hyperpigmented within 2 weeks. At 1 month of age, MRI revealed a small hypointense lesion on T(1)-weighted imaging, with water density on T(2)-weighted imaging, in the right centrum semiovale. At 4 months of age, her hyperpigmented lesions had faded, and at 7 months of age, MRI disclosed the disappearance of the previously observed abnormality. She exhibited no neurologic abnormalities. No cases have been reported concerning a transient lesion in the white matter revealed by MRI in incontinentia pigmenti. Although the pathogenesis is unknown, transient central nervous system involvement might have occurred in early infancy as did the fading skin lesions.