Subacute necrotizing encephalopathy (Leigh's disease): two unusual cases.

Two unusual cases of subacute necrotizing encephalopathy are described. In one, a marked hirsutism led to a suspicion of adrenal tumor or other endocrinopathy. In the other case, there was an agenesis of the corpus callosum, the second instance in which a malformation of the corpus callosum was associated with this condition. Electron micrographs from a case of Leigh's disease showed examples of marked axonal swelling and occasional splitting of the lamellae of the myelin sheath, probably responsible for the spongy state seen under light microscopy. That such marked changes were not seen in the "internal control" tended to exclude postmortem changes. The ultrastructure and histologic structure of striated muscle appeared normal in the one case examined.