ABSTRACT
<p><b>OBJECTIVE</b>To investigate the pathological characteristics of heroin spongiform leukoencephalopathy (HSLE).</p><p><b>METHODS</b>Cerebral tissue specimens were obtained from 15 patients with HSLE and the histological observations under optical and electron microscopes were carried out by HE, Bielschowsky's, and chromotrope 2R-brilliant green staining.</p><p><b>RESULTS</b>HSLE was characterized primarily by spongiform vacuolar degeneration of the cerebral white matter. Neurons in the gray matter, Purkinje and granular cells in the cerebella remain intact in all the cases. Numerous vacuoles, which merged to form larger cavities, appeared in the damaged white matter, and the axons survived in the deep white matter. The myelin sheath in the cerebellar white matter sustained more severe damages than those in the cerebral white matter. No vacuoles or lymphocyte infiltration occurred in the small peripheral vessels.</p><p><b>CONCLUSION</b>HSLE is pathologically characterized by vacuolar degeneration due to primary damage of the myelin, and the spongiform vacuolar degeneration is closely associated with the severity of demyelination in the white matter.</p>