Gastrointestinal AA amyloidosis secondary to chronic pyelonephritis presenting with refractory diarrhea and severe hypoalbuminemia.

Secondary amyloidosis is a rare complication of chronic inflammatory diseases, such as collagen diseases, and is often difficult to treat. In addition, the gastrointestinal tract is frequently involved in amyloid deposition that often results in various disorders and symptoms. A 70-year-old woman was admitted to our hospital with refractory diarrhea and hypoalbuminemia. Abdominal computed tomography demonstrated extensive edematous wall thickening of the small intestine and colon. Video capsule endoscopy revealed multiple ulcerations with a white mossy appearance of the ileum. Double-balloon endoscopy showed severe circumferential ulcers in the entire ileum. Histological examination of ileum biopsy samples revealed severe amyloid deposition in the lamina propria and perivascular areas of the submucosa. The patient was diagnosed with gastrointestinal AA amyloidosis. The cause of AA amyloid deposition was presumed to be chronic pyelonephritis due to ureteral stones that had been left untreated for 35 years. After treatment with ureteral drainage and antibiotics, the patient's symptoms and serological abnormalities improved dramatically. Here, we describe a case of severe gastrointestinal AA amyloidosis secondary to chronic pyelonephritis. Clinicians should thoroughly investigate the entire gastrointestinal tract in patients with refractory diarrhea and severe hypoalbuminemia considering the possibility of gastrointestinal amyloidosis.