Primary spinal primitive neuroectodermal tumor with extraneural metastases.

Cranial CT changes associated with metabolic and storage disorders have been well documented. However, until recently [1], CT findings in galactosemia had not been shown. Previous neuropathologic autopsy findings in galactosemia have been described by Crome [2] as a "microencephaly caused by a mainly burnt out gliotic encephalomyelopathy ." Hypothesized causes for this encephalopathy include hypoglycemia and competitive inhibition from hyperbilirubinemia or galactose-1-phosphate [3] . The toxic effect of galactose has been shown in animal models; it caused early and permanent injury to fetal nervous tissue and affected both growth and maturation [3] . Another study [4] showed the interference of galactose and galactitol in the metabolism of myelin constituents. In our patient , the dramatic reversibility of diffuse white-matter low attenuation suggests the presence of an interstitial intracerebral edema that is secondary to the toxic effect of galactose, perhaps because of osmolar effects as suggested by Belman et al. [1] . Another possibility for the intracerebral edema is that , with a dysmyelinating process , the loss of myelin , which is normally hydrophobic , causes an influx of water. The reversibility of edema coincided with initiation of a lactose-free diet and correlated with significant improvement in affected end organs, specifically the liver, spleen , lens, and CNS.