Reactive and degenerative changes of tissues surrounding a brain tumor.

We report here immunohistochemical and ultrastructural studies of the pattern of brain degeneration being a consequence of the presence of brain tumors. Robust microglial reaction with upregulation of MHC II type antigens within and around the brain tumor were seen along with the purely degenerative phenomena like neuroaxonal dystrophy (NAD) and myelin dilatation ("ballooning"). The reaction was monotonous and independent of the histological type of the brain tumor.

Krabbe disease: an ultrastructural study of globoid cells and reactive astrocytes at the brain and optic nerves.

We report here a detailed ultrastructural study of a brain biopsy along with post-mortem brain and optic nerve specimens from a case of Krabbe disease, a relatively rare leukodystrophy caused by a mutation in the gene for galactocerebrosidase (GALC) mapped to the 14q31 region of chromosome 14. GALC is responsible for lysosomal hydrolysis of several galactolipids including galactosylceramide, a major sphingolipids of the white matter of the central nervous system, galactosylsphingosine (psychosine) and galactosyldigluceride. The main neuropathological features such as accumulation of globoid cells, loss of myelin and marked gliosis were observed in the white matter. The monocytic origin of globoid cells was confirmed by CD-68 and ferritin-positivity and periodic acid Schiff (PAS) positivity. Ultrastructural study of the globoid cells showed the accumulation of tubular crystalloids, which are highly specific for this disease. The differences with Gaucher's disease and the pathomechanism of neuropathological damage are discussed.