Renal amyloidosis. Histological differentiation based on chemical types compared to Reimann's classification

13 cases of renal amyloidosis were reclassified on the basis of the chemical types of the major amyloid fibril proteins. The classification (primary, secondary) depending on the absence or presence of a coexisting disease was found not to correlate with the classification based on the chemical types (AL, AA). It is concluded that in association with a disease capable of inducing amyloidosis amyloid of type AA does not necessarily appear. The deposited amyloid may be of AL type. No difference of decisive importance between the AL and the AA type was observed concerning the tissue distribution of the amyloid within the kidney. With respect to the cause of death, however, a significant difference was found between the chemical types. In amyloidosis of AA type, the cause of death was always renal insufficiency, whereas in the cases of AL type cardiac or hepatic insufficiency led to death. Differentiation of the types of amyloid proteins has gained practical importance, as it offers the possibility of selective therapeutic approaches. Their routine differentiation is possible with the potassium permanganate method.