Involvement of the central nervous system and its coverings in different forms of amyloidosis.

The list of human amyloidoses contains at least ten different types that might be differentiated on account of their pattern of distribution (localized or generalized), on the basis of their underlying diseases and above all on account of their different amyloidogenic proteins. According to WRIGHT it was already possible to differentiate two types of amyloid by pretreating the histologic tissue sections with KMnO4 before staining them with Congored. But now nearly all different types of amyloid can be determined immunohistologically by means of specific antibodies. In the human brain and in its coverings we found as well localized as generalized amyloidoses. The most frequent localized amyloidosis is the cerebral amyloidosis in Alzheimer's disease, in senile dementia of the Alzheimer type and in "normal" aging (type ASb). The endocrine type of amyloid could be detected in the anterior pituitary lobe of old people and sometimes in adenomas of the pituitary gland (type AE). In cases of generalized amyloidosis (e.g. amyloid type AA, type AF or type AL) the intracranial amyloid deposits or precipitations are only found in those regions where the blood brain barrier is insufficient. These regions are --choroid plexus --infundibulum (hypothalamus) --pineal gland (epiphysis) --area postrema --circumventricular organs --ganglion Gasseri and --dura mater. The other parts of the CNS (the leptomeninges, cortical grey matter, subcortical white matter and basal ganglia) are always free of amyloid in these cases of generalized amyloidosis. In cases of cerebral amyloidosis (type ASb) the typical berefringent Congored deposits are found in the leptomeninges and in cortical and subcortical grey matter; white matter and all other regions are always free of amyloid. We observed several cases with more than one type of amyloidosis: e.g. a generalized form and a second local amyloidosis, two generalized forms (AA and A beta 2M) or even several localized types (ASb, AE). By paying attention to the typical distribution pattern of the amyloid deposits in the CNS and its coverings and by using specific antibodies it is now possible to distinguish between two different amyloidoses even in the same body region, e.g. in the human brain.