Histopathological analysis of four autopsy cases of HTLV-I-associated myelopathy/tropical spastic paraparesis: inflammatory changes occur simultaneously in the entire central nervous system

Although brain lesions have been described in some cases with HTLV-I-associ ated myelopathy/tropical spastic paraparesis (HAM/TSP), little is known abo ut the nature of brain lesion and its relation to the spinal cord lesion. I n the present study, we performed histopathological analysis of the brain a nd the spinal cord of four autopsied cases with HAM/TSP to clarify the rela tionship between the brain and the spinal cord lesions. In two cases with a ctive-chronic inflammation in the spinal cord, perivascular inflammatory in filtration was also seen in the brain, and the composition of cell subsets was similar both in the spinal cord and in the brain. No active inflammator y change was seen in the brain in two cases with inactive-chronic spinal co rd lesions. Inflamed vessels were distributed mainly in the deep white matt er and in the area between cerebral cortex and white matter of the brain. I n the spinal cord inflamed vessels were mainly seen in the bilateral latera l and the ventral posterior columns. Parenchymal infiltration was diffused in the spinal cord but very sparse in the brain, suggesting the importance of parenchymal infiltration in the destruction of tissues. These results su ggest that inflammatory changes occurred simultaneously in the spinal cord and in the brain, and that distribution of inflamed vessels closely correla ted with the characteristics of vascular architecture of the brain and the spinal cord, which lead to a slow blood flow. This study may help promote a better understanding of the pathogenesis of HAM/TSP.