図４〜図６は省略．この症例の所見は3つ．１）肝周囲に腹水がある（図１と図２：※）．２）図１〜図３で門脈周囲の低濃度所見（↑）periportal lucency（tracking），門脈を全周性に取り巻いている低濃度所見だから胆管ではない．下大静脈（IVC）周囲にも同様な所見を認める（白矢印）．３）漿膜下浮腫（subserosal edema）による胆嚢壁の肥厚（▲）である．胆嚢内腔の拡張による腫大はなく，周囲脂肪組織の濃度上昇もなく急性胆嚢炎ではない．Periportal lucencyは門脈周囲の浮腫や液貯留を意味し，肝炎，心不全，外傷などで見られると言われる．胆嚢のsubserosal edemaによる壁肥厚は胆嚢炎だけでなく肝炎，心不全，腹水，門脈圧亢進症や右腎盂腎炎などでも認められる所見で，胆嚢炎と誤診しないよう注意を要する．原因不明の肝炎であった．

参考症例（黄色肉芽腫性胆嚢炎：xanthogranulomatous cholecystitis）：72歳女性．数日間心窩部痛が持続するので来院した．図３〜図１１で胆嚢の局所性の著明な壁肥厚を認める（↑）が，病理所見は黄色肉芽腫性胆嚢炎（xanthogranulomatous cholecystitis）であった．

文献考察：黄色肉芽腫性胆嚢炎（Xanthogranulomatous cholecystitis）
１）岩崎誠：黄色肉芽腫性胆嚢炎．胆道疾患，肝・胆・膵の外科：疾患編，水本龍二 監修，医学図書出版，東京，128-129，1994．
要旨：胆嚢壁内に肉芽腫を形成する胆嚢炎で，組織学的にはfoam cellあるいはxanthoma cellと呼ばれる，胆汁を貧食して黄色色素を含む組織球を主体とした肉芽腫性炎症である．頻度は全胆嚢摘出例の5％以下とまれで，50-60歳の男性に多い．胆石の合併症は80-91％と高い．胆嚢結石の嵌頓などに伴う胆嚢内圧の上昇により，Rokitansky-Aschoff sinusや粘膜損傷部から胆汁が胆嚢壁内へ浸潤し，組織球がこれを貧食して肉芽腫が形成され，さらに異物性反応，線維化へと進む．肉芽腫は急性胆嚢炎の発症後3〜4週目頃より形成され，炎症性浸潤を伴って肝床側へ伸展し胆嚢癌との鑑別が困難となることがある．CA19-9が13.6％に陽性となる．胆嚢癌の合併率は約7％．

２）黄色肉芽腫性胆嚢炎のCT所見
AJR Am J Roentgenol. 2000 Apr;174(4):979-83.
Xanthogranulomatous cholecystitis: clinical, sonographic, and CT findings in 26 patients.
Parra JA, Acinas O, Bueno J, Guezmes A, Fernandez MA, Farinas MC.

OBJECTIVE: The purpose of our study was to evaluate the sonographic and CT features of xanthogranulomatous cholecystitis, correlating the pathologic and surgical findings. MATERIALS AND METHODS: Xanthogranulomatous cholecystitis was pathologically diagnosed in 26 patients from January 1996 to August 1998. The patients were 15 women and 11 men with a mean age of 63 years. All patients had preoperative sonography and nine also underwent CT In five patients, sonography was performed on the surgical specimen. Clinical indications for imaging included cholecystitis (14 patients), biliary colic (six patients), stone-induced pancreatitis (three patients), tumor (two patients), and gallstone ileus (one patient). RESULTS: The most characteristic sonographic finding, confirmed by sonographic study of the surgical specimens, was the presence of hypoechoic nodules or bands in the gallbladder wall, which were seen in 35% of the patients. Cholelithiasis and a thickened gallbladder wall were frequent findings. The most characteristic (specific) CT finding was a hypodense band in the gallbladder wall, seen in 33% of the patients. Two of twelve patients who underwent laparoscopic cholecystectomy required conversion to open surgery. CONCLUSION: Although the preoperative imaging diagnosis of xanthoganulomatous cholecystitis is difficult, the presence of hypoechoic nodules or bands in the gallbladder wall on sonography or of a hypodense band around the gallbladder on CT, is highly suggestive of this disease.PMID: 10749233