[An autopsy case of dementia lacking distinctive histology showing semantic dementia]

We report an autopsy case of dementia lacking distinctive histology (DLDH) showing semantic dementia. At age 47, a Japanese man developed aspontaneity, followed by semantic dementia a few months after the onset. Thereafter he developed disinhibition and the language disturbance, which progressed transcortical sensory aphasia and terminally mixed transcortical aphasia. At age 48, about 10 months after the disease onset, neurological examination revealed frontal signs and hyperreflexia in the four extremities and 4 months later, the patient presented with mild rigidity in the right upper and lower extremities. At age 49, 1 year and 8 months after the onset of the disease, he could not walk by himself. At age 50, 2 years and 8 months after the onset, he died of pneumonia. The brain weighed 1350 g. Macroscopically, atrophy of the frontal lobes and temporal lobes, predominant in the left, was evident. The caudate nucleus was severely atrophic, in addition to the depigmentation of the substantia nigra. Neuronal loss and astrocytosis was obvious in the cerebral cortex, prominently in the frontotemporal lobes, amygdala, caudate nucleus, putamen, pallidum, thalamus, and substantia nigra. In the caudate nucleus, prominent neuronal loss with fibrillary gliosis was obvious. Senile plaques, neurofibrillary tangles, Pick bodies, astrocytic plaques, and tufted astrocytes were not found by Gallyas and tau staining. Ubiquitin-immunoreactive intracytoplasmic inclusions were not encountered in the hippocampal dentate gyrus and superficial layers in the frontotemporal cortex. On the basis of meticulous perusal of the literature, we believe that our case is the first autopsy case of DLDH reported in Japan.