慢性関節リウマチの経過中に小腸・大腸に病変がみられた続発性アミロイドーシスの1例

Amyloidosis Involving the Small and Large Bowel during the Course of Rheumatoid Arthritis, Report of a Case

要旨　66歳，男性の続発性アミロイドーシスの1例を報告した．4年前より慢性関節リウマチのために消炎鎮痛剤および金剤による治療を受けていたが，水様下痢，悪心，嘔吐を認めるようになった．診察上は貧血と充進した腸蠕動音を聴取した．入院時検査所見では便潜血が強陽性で，核左方移動を伴う白血球増多，貧血，α₂-gl分画の上昇を伴う低蛋白血症，赤沈充進，CRP強陽性を認め，便細菌培養は正常であった．腹部単純X線検査では著明な小腸ガス像とニボー形成がみられた．上部消化管内視鏡検査では胃角部に潰瘍を認めたものの食道，胃，十二指腸の生検では異常は認めなかった．小腸X線検査では充満像でKerckring皺襞の肥厚を，また二重造影では腸管の辺縁不整とびまん性の顆粒状透亮像がみられた．プッシュ式小腸内視鏡検査による上部空腸の観察ではKerckring皺襞の消失と粘膜面の凹凸不整，散在性の出血斑を認め，粘膜生検によりアミロイドの沈着が証明された．また，大腸X線検査では異常所見は得られなかったが，大腸内視鏡検査では下部大腸に散在性の出血斑がみられ，直腸生検によりアミロイドの沈着が証明された．

　Watery diarrhea, nausea and vomiting occurred in a 66-year-old male with a history of rheumatoid arthritis of 4-years' duration. He had been treated with analgesics and gold derivative.

　Physical examination revealed anemia and increased bowel sounds. Fecal occult blood test was strongly positive. Urinary protein was slightly positive. Peripheral blood examination revealed increased WBC count, 10,130 /mm³, with shift to the left ; hemoglobin was 11.3 g/dl, and hematocrit 33.9%. Total protein was 4.8 g/dl with decreased albumin and increased alpha-2 globulin fraction. ESR was 35 mm/hr, CRP 6 (+), and RA-test 1 (+). Culture of the stool was negative for bacteria.

　Abdominal plain film revealed distended small bowel with gas and niveau formation. Upper GI endoscopy revealed only a healing stage gastric ulcer at the angle. Mucosal biopsies from the esophagus, stomach and duodenum were negative for amyloid deposits.

　Enteroclysis was performed revealing thickened Kerckring's folds, irregular contour of the intestinal loops, and granular translucencies. Small bowel endoscopy with SIF-10 disclosed loss of Kerckring's folds and irregular mucosal surface with petechiae ; mucosal biopsy revealed amyloid deposits in the lamina propria and submucosa.

　Barium enema x-ray did not show any abnormality. Colonoscopy, however, disclosed mucosal petechiae from the rectum to the descending colon. Rectal biopsy disclosed amyloid deposits. These findings established the diagnosis of amyloidosis secondary to rheumatoid arthritis.

　There is a few reports on the enteroscopic findings of amyloidosis. An outstanding feature of our case is the presence of mucosal petechiae in the small and large intestine. There is only one case reported in which mucosal petechiae were observed in the colon ; however, such finding has not yet been reported for the small intestine.