Plaque-like structures and arteriosclerotic changes in "diffuse neurofibrillary tangles with calcification" (DNTC)

"Diffuse neurofibrillary tangles with calcification" (DNTC) is a rare form of slowly progressive dementia characterized by temporal or fronto-temporal atrophy with neuronal loss and astrocytosis, neurofibrillary tangles and F ahr-type calcification, but no senile plaques in the cerebral cortex. In pa tients with DNTC, we detected a novel histopathological abnormality that we termed "plaque-like structures" (PLS). PLS appeared as oval, slightly eosi nophilic masses of up to 100 mum in diameter. With methenamine silver stain , the PLS were argyrophilic, and thread-like structures were observed in an d around them. Most PLS were observed in deep layers of the cortex and subc ortical white matter, and were accompanied by small vessels. They were inti mately associated with the small-vessel walls and astrocytes. They were com posed of two types of fibers. The first type comprised straight and loosely interwoven fibers about 25-30 nm in diameter, while the other type evoked tangles. These structures have not been found in other neurodegenerative di seases, including Alzheimer's disease. In addition, to evaluate hyaline art eriosclerosis in DNTC, we examined sclerotic changes of the medullary arter ies and assessed white matter lesions in affected patients. In three of fou r patients with DNTC, sclerosis of the medullary arteries was significantly more extensive than in age-matched controls. In all four patients, the sev erity of white matter lesions was graded as moderate or severe in the tempo ral lobe and as mild or moderate in the frontal lobe. Arteriosclerotic chan ges and white matter lesions can occur without hypertension and beta amyloi d deposits in DNTC.