The liver is usually affected when amyloid disease exists in the body, but the affection shows great differences in degree. It may be very slight in the liver while very advanced in the spleen and kidney, and vice versa. It is not known how these differences are determined. In phthisis pulmonalis, which is the most frequent cause of amyloid disease, we have all varieties in distribution.
The degeneration appears first in the arteries and capillaries, the appearance in the latter being as if, at intervals, the wall were swelled up by a translucent material. In these earlier stages there is no difficulty in making out that inside the lobules it is the capillaries which are affected. The general arrangement of the capillaries is beautifully shown by the rose-pink colour in a section stained with methylviolet, the appearance being almost that of an injected specimen. Even in the earlier periods considerable atrophy of the hepatic cells can be observed as a result of pressure from the swollen capillaries, and the atrophic cells frequently contain fat. In advanced stages the cells are very greatly destroyed, so that the liver tissue is replaced by amyloid substance. The tissue still shows indications of the lobular arrangement, and also of the capillaries, although scarcely any hepatic cells remain (see Fig. 50, p. 147).
It is remarkable that, with this great loss of the secreting substance, there is actual increase in size and weight of the liver. It is not uncommon to find the liver weighing two or three times the normal. The increase in size is not proportionate to that in weight, as the amyloid substance is of greater density than the liver tissue. The edges of the organ are rounded and its consistence elastic and resistant. The surface, and especially the cut surface, is homogeneous and presents a peculiar translucent waxy appearance, which in advanced stages is highly characteristic.