若杉 聡¹, 平田 信人¹, 小宮 雅明², 北浦 幸一², 山崎 智子², 神作 慎也², 本間 善之², 加納 宣康³, 成田 信⁴, 星 和栄⁴

Satoshi WAKASUGI¹, Nobuto HIRATA¹, Masaaki KOMIYA², Kouichi KITAURA², Tomoko YAMAZAKI², Shinya KANSAKU², Yoshiyuki HONMA², Nobuyasu KANOU³, Shin NARITA⁴, Kazuei HOSHI⁴

¹亀田総合病院消化器内科, ²亀田総合病院超音波検査室, ³亀田総合病院外科, ⁴亀田総合病院病理

¹Division of Gastroenterology, Department of Internal Medicine, Kameda Medical Center Hospital, ²Ultrasonography Room, Kameda Medical Center Hospital, ³Department of Surgery, Kameda Medical Center Hospital, ⁴Department of Pathology, Kameda Medical Center Hospital

キーワード : ultrasonography, adenomyomatosis, xanthogranulomatous cholecystitis

胆嚢壁内に類円形高エコー結節を認めた胆嚢疾患3例の臨床的特徴，画像，病理組織所見を検討した．全例に腹痛ないし背部痛など胆嚢炎に関連する症状を認めた．結節を胆嚢全体に認めた症例が2例，体部のみに認めた症例が1例だった．全例結石を認めなかった．CTは全例で行われ，単純CTでは3例中2例で結節は軽度高濃度だった．MRIは全例で行われ，結節はT1強調像で高信号を呈した．病理組織診断は，全て慢性胆嚢炎を伴う胆嚢腺筋腫症だった．拡張したRokitansky-Aschoff sinus（以下，RAS）周囲の線維化が強く，最近の炎症の存在が推察された．1例は胆嚢底部に膿瘍も形成していた．この膿瘍部分は超音波検査で境界不明瞭な淡い高エコー結節だった．壁内の類円形高エコー結節は，RAS内に充満した濃縮胆汁，結石，膿瘍に相当すると思われた．胆嚢腺筋腫症に炎症が加わるとRASの出口が浮腫，線維化で狭窄し，RAS内の胆汁の流出障害が生じ，濃縮胆汁，結石などが形成される．その過程でRASが破綻した場合，膿瘍が形成されると考えた．破綻していないRASは境界明瞭な高エコー結節を呈するが，破綻し膿瘍を形成したRASは境界不明瞭になると考えた．黄色肉芽腫性胆嚢炎は，破綻したRASや胆嚢粘膜から壁内に胆汁が流入し，膿瘍が形成され，吸収される過程で生じる．大部分は結石が原因であるが，結石を伴わない症例も存在し，今回提示した3例は結石を認めない黄色肉芽腫性胆嚢炎の原因を推察する上で重要と思われた．

We report our experience with 3 cases of gallbladder disease accompanied by hyperechoic nodules of the gallbladder wall in ultrasonographic images. All 3 patients complained of abdominal pain or back pain. Hyperechoic nodules were observed throughout the gallbladder wall in 2 patients, and a hyperechoic nodule was found in the body of the gallbladder of the third patient. Abdominal CT was performed in all 3 cases, and plain CT revealed high density nodules in 2 cases. MRI was performed in all cases, and in all of them, all of the hyperechoic nodules were high intensity in T1WI. The pathology in all cases was diagnosed as adenomyomatosis accompanied by chronic cholecystitis. Abscess was detected in fundus in one case, but it was unclear and poorly demarcated in the ultrasonic images. Demarcated hyperechoic nodules in the ultrasonographic images were thought to be Rokitansky-Aschoff sinus (RAS) with concentrated bile or sludge, or minute stones. An unclear hyperechoic nodule with an irregular margin was thought to be an abscess. We concluded that a hyperechoic nodule in gallbladder wall was RAS with inflammation. Xanthogranulomatous cholecystitis (XGC) is thought to result from rupture of the RAS, and almost all cases of XGC are accompanied by gallstones. But the cause of XGC when no gallstones are present is not known. The 3 cases reported here would appear to be a precursor stage of XGC.