Colonic Amyloidosis

Image of the Month Colonic Amyloidosis JARED M. BRAUNSTEIN, ALI AMAN, and JOHNATHAN WARMAN Lenox Hill Hospital, New York, New York

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66-year-old man with no significant medical history presented to the emergency department with a 3-day history of bloody diarrhea. He denied abdominal pain, nausea, vomiting, or fever. The patient also denied history of inflammatory bowel disease or recent antibiotic use. Laboratory tests revealed severe anemia, acute renal failure with nephrotic-range proteinuria and hypoalbuminemia. Urine and serum protein electrophoresis revealed no M-spike. Colonoscopy revealed patchy erythematous, friable, and granular-appearing mucosa throughout the colon (Figure A). The initial endoscopic impression was probable ischemic colitis; however, histology revealed colonic amyloidosis (Figure B). There was strong birefringence with Congo red stain (Figure C), and immunohistochemistry confirmed the presence of AA type amyloid fibrils consistent with secondary amyloidosis. Gastrointestinal amyloidosis can present as gastrointestinal hemorrhage,1 chronic intestinal dysmotility, malabsorption syn-

dromes, and protein-losing enteropathy. The symptoms and findings are nonspecific and resemble those of inflammatory bowel disease and ischemic colitis. Primary AL type and secondary AA type gastrointestinal amyloidosis can be indistinguishable clinically. Primary amyloidosis is seen in the setting of plasma cell dyscrasias, whereas secondary amyloidosis is usually associated with chronic inflammatory arthritides and inflammatory bowel disease. Endoscopically, both can present as fine granular mucosa, polypoid protrusions, or ulcerating/friable mucosa. Radiographically, secondary amyloidosis has a fine granular pattern, whereas primary amyloidosis appears as polypoid protrusions and thickened folds.2 AA type amyloid fibrils tend to involve myenteric plexus with minimal muscle infiltration, whereas AL fibrils deposit extensively in muscularis propria.3 Special staining and immunohistochemistry can also help in making this distinction. References 1. Gillmore JD, Booth DR, Madhoo S, et al. Hereditary renal amyloidosis associated with variant lysozyme in a large English family. Nephrol Dial Transplant 1999;14:2639 –2644. 2. Araoz PA, Batts KP, MacCarty RL. Amyloidosis of the alimentary canal: radiologic-pathologic correlation of CT findings. Abdom Imaging 2000;25:38. 3. Tada S, Iida M, Yao T, et al. Intestinal pseudo-obstruction in patients with amyloidosis: clinicopathologic differences between chemical types of amyloid protein. Gut 1993;34:1412.

Special thanks to Knarik Arkun, MD. © 2007 by the AGA Institute 1542-3565/07/$32.00 doi:10.1016/j.cgh.2007.02.026 CLINICAL GASTROENTEROLOGY AND HEPATOLOGY 2007;5:xxx