Incidence and origin of non-systemic microdeposits of amyloid.

In a general hospital, 391 consecutive necropsies in which at least seven organs were available, were examined retrospectively by polarizing microscopy of Congo-red-stained sections for the presence of local amyloid deposits.Non-systemic microdeposits of amyloid were encountered in 72 cases, an overall incidence of 18.4%. They were usually small and frequently detectable only by virtue of polarizing microscopy. There is no indication that these microdeposits of amyloid are of pathogenetic significance. Although they sometimes occur in more than one organ, such deposits can be readily distinguished from those of systemic amyloidosis by their histological features.