We report an autopsy case of HHV6-induced encephalomyelitis that developed after BMT. The patient was a 61-year-old man with acute myeloid leukemia, who developed disorientation
and short-term memory disturbance 35 days after allogenic BMT. MRI demonstrated T1-weighted high-signal intensity lesions in the medial temporal lobe and thalamus, and PCR of the CSF disclosed an increase in the copy numbers of the HHV6 genome. The patient died after a clinical course of 6 months, and at autopsy the brain showed remarkable atrophy of the hippocampus. Histopathologically, neuronal loss with astrocytosis and patchy necrosis with infiltration of macrophages were found predominantly in the hippocampus, Hedgehog antagonist amygdala, mamillary body, claustrum, and thalamus. Perivascular and intraparenchymal lymphocytic infiltration was slight.
Similar lesions were also scattered in the cerebral neocortex, midbrain, pontine base, cerebellar white matter, and lumbar cord. In some of these lesions, axons were relatively preserved in comparison with myelin sheaths. Significant increase in the copy numbers of the HHV6 genome was demonstrated in the postmortem brain tissue by PCR. Neuropathological features of the present case were similar to those described in previously reported cases, but the distribution of lesions was more widespread. Demyelination was supposed to be involved in the pathogenesis of some of the lesions. this website “
“CADASIL is a generalized angiopathy caused by mutations in NOTCH 3 gene leading to degeneration and loss of vascular smooth muscle cells (VSMC) in small arteries and arterioles. Since the receptor protein encoded by NOTCH 3 gene is expressed not only on VSMC but Protein kinase N1 also on pericytes, pericytes and capillary vessels can be damaged by CADASIL. To check this hypothesis
we examined microvessels in autopsy brains and skin-muscle biopsies of CADASIL patients. We found degeneration and loss of pericytes in capillary vessels. Pericytes were shrunken and their cytoplasm contained numerous vacuoles, big vesicular structures and complexes of enlarged pathological mitochondria. Degenerative changes were also observed within endothelial-pericytic connections, especially within peg-and-socket junctions. Nearby pericyte cell membranes or inside infoldings, deposits of granular osmiophilic material (GOM) were usually seen. In the affected capillaries endothelial cells revealed features of degeneration, selective death or swelling, leading to narrowing or occlusion of the capillary lumen. Our findings indicate that in CADASIL not only VSMC but also pericytes are severely damaged. Pericyte involvement in CADASIL can result in increased permeability of capillary vessels and disturbances in cerebral microcirculation, leading to white matter injury.