2）放線菌感染症（Abdominopelvic actinomycosis）

Abdominopelvic Actinomycosis

要旨　腹部放線菌症は口腔内常在菌であるActinomyces Israeliiが消化管粘膜から侵入し感染が成立する．特に最近では不妊器具（IUD）や魚骨が腸管穿通し本症を来す報告がある．臨床症状は一般的に腹痛，発熱など非特異的であるが腫瘤触知，瘻孔形成がみられることもある．画像診断では腸管壁外を主体に炎症性腫瘤を形成し，なおかつ炎症が腸管壁内にまで及ぶ所見を捉えることが重要であり，注腸X線検査，内視鏡，CTが有用である．鑑別疾患としては憩室炎，腸間膜脂肪織炎，びまん性浸潤性大腸癌，悪性リンパ腫，転移性大腸癌が挙げられる．確定診断は腫瘤内膿汁や組織から放線菌塊（Drüse）を証明することでなされるが困難なことも多い．治療は外科的切除に加えたペニシリンなどの抗生剤投与を行うことにより予後は良好である．

　Actinomycosis is a chronic suppurative disease caused by an anaerobic bacterium, most commonly Actinomyces Israelii, invading from the gastrointestinal mucosa. It has become more prevalent recently. Several cases have been reported associated with the use of intrauterine contraceptive devices (IUD), and penetration by fish bones. Clinical symptoms are non-specific, generally including abdominal pain and fever, rarely abdominopelvic mass or fistulization. Barium enema, endoscopy, and computed tomography can be helpful for its diagnosis, because this disease consists of an extraluminal inflammatory mass infiltrating to the intestinal wall. Actinomycosis is frequently misdiagnosed as diverticulitis, mesenteric panniculitis, diffuse infiltrating colonic cancer, malignant lymphoma, or metastatic colonic tumor. The identification of sulfur granules from resected specimens or abscesses is conclusive evidence for a diagnosis of actinomycosis. The treatment that has been reported for actinomycosis is long-tem maintenance of penicillin after surgical excision of the affected tissues. This treatment has resulted in a high cure rate.