Proton MR spectroscopic characteristics of a presumed giant subcortical heterotopia.

A newborn presented with a mass replacing the left cerebral hemisphere. Although the internal signal characteristics of the lesion were suggestive of disorganized gray and white matter, a true neoplasia such as a ganglioglioma could not be totally excluded. Biopsy is not recommended in these cases since the results may be misleading. Proton MR spectroscopy was used; this technique also suggested the hamartomatous nature of the lesion. Based on the clinical course and the imaging features, conservative therapy and observation were undertaken instead of surgery. At 6 months of age, the patient is stable and the lesion is unchanged.