軟部肉腫との鑑別を要した遺残ガーゼによる異物肉芽腫の2例

Gossypiboma Required of Differential Diagnosis to Soft Tissue Sarcoma : Reports of Two Cases

　抄録：遺残ガーゼによる異物肉芽腫（以下，gossypiboma）の2例について画像所見を中心に報告する．症例1は37歳の女性である．19歳時に腰椎椎間板ヘルニアの手術の既往がある．1999年10月，腰痛のためMRIを行い，左腰部傍脊柱筋内に腫瘤が認められた．2000年3月，切開生検時にガーゼ片を認め，gossypibomaと診断し腫瘤を摘出した．症例2は64歳の女性である．36歳時に右横隔膜穿孔の手術の既往がある．2000年7月，健康診断にて右背部腫瘤を指摘された．2001年11月，切開生検を行い，病理組織検査で異物肉芽腫と診断され腫瘤摘出術を施行した．術後標本で遺残ガーゼを確認した．2例に共通するMRI所見は①境界明瞭な卵円形の腫瘤である，②T2強調像で不均一な内部構造を示す，③中心部がGd-DTPAで造影されないことであった．これらは，壊死を伴う悪性腫瘍にもみられる所見であり，gossypibomaが疑われた場合でも，生検による病理学的診断が必要である．

　The authors report two cases of retained surgical sponge (gossypiboma) with special reference to MRI features. Case 1. A 37-year-old woman, who had undergone a lumber discectomy at the age of 19, complained of lower back pain in October 1999. MRI demonstrated a mass in the left paravertebral muscle. In March 2000, we performed an incisional biopsy and macroscopically confirmed small cotton fibers. The mass was excised and microscopically diagnosed as a foreign body granuloma. Case 2. A 64-year-old woman, who had undergone a surgery on the right chest wall at the age of 36, was found to have an incidental mass in her right back at a medical checkup in July 2001. In November 2001, we performed an incisional biopsy and diagnosed the mass as a foreign body granuloma by microscopic examinations. The cut sections of the excised mass revealed retained surgical gauze. In both cases, MRI revealed a sharply defined oval lesion, heterogeneous intensity on T2-weighted images, and peripheral enhancement by Gd-DTPA. These features would agree with the suspicion of a soft-tissue sarcoma with central necrosis. When we encounter a soft-tissue mass suggestive of a gossypiboma by past history, we recommend a microscopic examinations on whole cut sections.