[An adult case of classical Pelizaeus-Merzbacher disease--magnetic resonance images and neuropathological findings].

A 26-year-old man was first noticed to have slowly progressive difficulty in walking and speaking at the age of 19 years. When he was 26 years old, a neurological examination showed mild dementia, nystagmus, ataxic speech together with ataxic and spastic gait. The T2-weighted MR images demonstrated increased signal areas with sparing of small areas in the brain white matter. He expired suddenly at his age of 26 years. The neuropathological study revealed the mildly atrophic brain with "tigroid" demyelination. Patchy demyelinated foci were found in the cerebellum, brain stem and spinal cord. The myelin around blood vessels and axons were generally well preserved. Oligodendrocytes were decreased in the demyelinated areas. A diagnosis of classical Pelizaeus-Merzbacher disease was neuropathologically made, in spite of uncertainty of family history and late onset. Because MR images are identical with the neuropathological findings of "tigroid pattern", MR imaging can contribute to the clinical diagnosis of this disease. This is the first report in which brain MR images are compared with neuropathological findings in a case of classical P-M disease.