DISTINCTIVE CASE - INTESTINAL PSEUDOOBSTRUCTION AND ISCHEMIA SECONDARY TO BOTH BETA(2)-MICROGLOBULIN AND SERUM-A AMYLOID DEPOSITION

We present the case of a 61-year-old man on long-term hemodialysis in whom early colonic ischemia and pseudo-obstruction were caused by amyl oid deposition of both the beta(2)-microglobulin and AA type, The ligh t microscopic diagnosis of amyloidosis was confirmed by Congo red bire fringence, immunohistochemistry, and electron microscopy. The two type s of amyloid had separate distributions within the colon, While both t ypes affected submucosal and serosal blood vessels, the beta(2)-microg lobulin amyloid also formed large masses that displaced smooth muscle cells and was associated with Class II major histocompatibility-positi ve multinucleated giant cells, The pathogenesis of this uncommon occur rence of two amyloids and the role of chronic inflammation in amyloido genesis are discussed.