アミロイドーシスにおける上部消化管病変の特徴

Clinicopathologic Analysis of the Upper Digestive Tract Lesions in Patients with Amyloidosis

要旨　アミロイド沈着が証明された72例の上部消化管病変を臨床病理学的に検討した．72例のアミロイド蛋白を免疫組織学的およびKMnO₄前処理Congo red反応により検索した結果，アミロイドA蛋白（AA型）52例，免疫グロブリンL鎖（AL型）14例，β₂-ミクログロブリン（AH型）3例，異型プレアルブミン（AF型）3例であった．X線・内視鏡所見は蛋白別に有意な差がみられ，AA型では微細顆粒状隆起の多発する粗ぞうな粘膜が，AL型では粘膜下腫瘤様隆起の多発と皺襞の肥厚が，それぞれ十二指腸を中心に高率に認められた．組織像との対比では，沈着が軽度の症例では粘膜面の異常に乏しく，沈着が進むにつれてAA型では粘膜固有層への広範顆粒状の沈着を，AL型では粘膜筋板・粘膜下層および固有筋層への塊状沈着を認め，各々の形態学的特徴像および臨床徴候との対応がみられた．また，AH型では固有筋層への多量沈着が，AF型では自律神経節への沈着が臨床症状に強く関与していると考えられた．72例の生検におけるアミロイド沈着陽性率は十二指腸（97％），胃（89％），食道（52％）の順に高く，沈着の程度もこの順に高度であった．以上の成績から，上部消化管はアミロイドーシスの診断に極めて適した検査部位であり，特に十二指腸第2部の微細な形態学的変化を捉えることにより，アミロイド蛋白の種類と沈着の程度を推測することが可能であると考えられた．

　Clinicopathologic findings of the upper digestive tract lesions were studied in 72 patients with amyloidosis according to the chemical type of amyloid protein. Radiographic and endoscopic examinations of the upper digestive tract revealed various findings such as a coarse mucosal pattern with innumerable fine granular elevations, erosions, shallow ulcers, mucosal friability, thickening of the folds, and multiple polypoid protrusions. Immunohistochemical study of the biopsy specimens identified the following chemical types: amyloid A protein (AA) in 52 cases, light chain protein (AL) in 14,β₂-microglobulin (AH) in three, and atypical prealbumin (AF) in three, Considerable differences were found between chemical types of amyloid protein. The AA cases produced a coarse mucosal pattern with innumerable fine granular elevations, which reflected expansion of the lamina propria by amyloid deposits. Multiple polypoid protrusions and invariable thickening of the folds were evident only in the AL cases, correlating with massive amyloid deposits in the muscularis mucosae and submucosa. The AH and the AF cases produced gastric retention, relating to extensive amyloid deposits in the muscularis propria in the AH, and in the myenteric plexuses in the AF. Clinically, a more frequent occurrence of diarrhea, malnutrition, and occult blood in stools was present in the AA cases, whereas dysphagia with macroglossia and chronic intestinal pseudo-obstruction were evident only in the AL and the AH cases. These results suggest that clinicopathologic differences between the chemical types exist in patients with amyloidosis and that characteristic radiographic and endoscopic changes of chemical types can be detected well in the upper digestive tract.