ドロレス顎口虫の大腸壁内迷入によるイレウスの1例

Ileus Caused by Gnathostoma doloresi Larvae Invading the Colonic Wall, Report of a Case

要旨　患者は57歳，男性．主訴は腹痛．腹部単純X線写真でniveauを認めたため，イレウスの診断で入院となる．保存的治療によりイレウス状態は改善したが，注腸造影上，上行結腸肝彎曲部近くにBorrmann I型の腫瘤陰影を認め，大腸癌を否定できないため，開腹手術により，同部を中心に前後約15cmの上行結腸横行結腸切除術を施行した．肉眼的には，漿膜面に約4cm径の小出血像を伴う白境界不鮮明な腫瘤を認めた．組織学的には，同腫瘤は漿膜下組織を中心として，筋層，粘膜下組織へ拡がる著明な好酸球性の炎症像から成り，組織標本の1つに径0.2mmの寄生虫断面を認めた．実体顕微鏡下で，ほぼ完全な虫体を取り出すことができ，ドロレス顎口虫第3後期幼虫と断定された．これまでに知られているドロレス顎口虫症のほとんどは皮膚爬行症として発症しており，大腸壁内迷入によりイレウスを引き起こきしたと考えられる症例は本報告が初めてである．

　A 57-year-old man living in Miyazaki Prefecture visited a primary physician because of severe abdominal pain. He had eaten a few slices of the flesh of a snake, Agkistrodon halys one week previously. Plain abdominal radiogram revealed multiple gas-fluid levels with distended bowel in an inverted U-shape. He was transferred to the emergency ward of a regional hospital. Ileus was improved by strict prohibition of eating and drinking and care using hyperalimentation for a few days. Barium enema revealed a tumor resembling Borrmann type 1 in the ascending colon near the hepatic flexure. Since colonic ileus due to malignant tumor was strongly suspected, the tumor was surgically removed by simple colonic resection. Postoperative pathological examination revealed that the mucosal surface of the resected colon had neither ulceration nor bleeding except for slight edema. An irregular-shaped unencapsulated mass of about 4 cm in diameter was seen in the outer connective tissue. The mass was composed of massive infiltration of eosinophils, and an obliquely cut parasite body was found in one of the sections. An entire body of the larva of Gnathostoma doloresi in the advanced third stage was dissected out from the corresponding paraffin block. Since most of gnathostomiasis cases are found as a disease of the skin, this is an extremely rare form of gnathostomiasis.