Atypical amyotrophic lateral sclerosis with dementia mimicking frontal Pick's disease: a report of an autopsy case with a clinical course of 15 years.

This report concerns an autopsy case of atypical amyotrophic lateral sclerosis (ALS) with dementia mimicking frontal Pick's disease. The patient was a Japanese woman without hereditary burden who was 45 years old at the time of death. She developed abnormal behavior and amnesia at age 30, followed by disinhibition, aspontaneity, urinary incontinence, abulia, and rectal incontinence. Neurological signs compatible with ALS developed about 14 years after the disease onset. No respirator was used throughout the clinical course. Macroscopically, neuropathological examination showed atrophy of the frontotemporal lobes with accentuation in the convexities of the frontal lobes. Histologically, there was neuronal loss in the cerebral cortex, parahippocampal gyrus, amygdala, caudate nucleus, substantia nigra, brain stem motor nuclei, and anterior horns of the spinal cord, in addition to marked degeneration of the pyramidal tracts. Ubiquitin-immunoreactive neuronal inclusions were present in the frontotemporal cortical layer II neurons and motor neurons in the brain stem and spinal cord. In the hippocampal dentate granular cells, many ubiquitin-immunoreactive neurites were present without ubiquitin-immunoreactive intraneuronal inclusions. Based on these clinicopathological findings and a review of the literature, we concluded that our case was atypical ALS with dementia of long disease duration. We also note the possibility that motor neuron disease-inclusion dementia with a long clinical course may develop into ALS in the final stage of the illness.