伊藤 弘昭¹, 辻本 文雄², 市瀬 雅寿³, 桜井 正児³, 小池 淳樹⁴

Hiroaki ITO¹, Fumio TSUJIMOTO², Masatoshi ICHINOSE³, Masaru SAKURAI³, Junki KOIKE⁴

¹聖マリアンナ医科大学消化器一般外科, ²聖マリアンナ医科大学臨床検査医学, ³聖マリアンナ医科大学病院超音波センター, ⁴聖マリアンナ医科大学診断病理学

¹Department of Gastroenterological & General surgery, St. Marianna University, School of Medicine, ²Department of Clinical laboratory medicine, St. Marianna University, School of Medicine, ³Department of Ultrasonography center, St. Marianna University, School of Medicine, Hospital, ⁴Department of pathology, St. Marianna University, School of Medicine

キーワード : desmoid tumor, MRI, elastography, ultrasonography, breast gland

胸壁デスモイド腫瘍が乳腺内発育を示したきわめて稀な症例を経験したので報告する．症例は30歳，女性．2006年2月に左乳房に腫瘤を自ら触知した．しだいに疼痛が増強してきたため，7月に当院を受診した．マンモグラフィは両側とも腫瘤及び悪性石灰化を示唆する所見は認めなかった．超音波検査は左乳房の深部に不整形の低エコー腫瘤を認め，硬癌を疑った．穿刺吸引細胞診はclassIIで，明らかな細胞異型は認めなかった．経皮的針生検は間質膠原線維の増殖と炎症細胞浸潤を認めたのみで悪性所見を認めなかった．MRIでは漸増型の造影パターンを呈し，MRSではコリンピークを認めないことから良性の線維組織が疑われた．再度施行された超音波検査ではエラストグラフィ及びダイナミックテストが追加された．エラストグラフィでは胸壁の横方向に広い腫瘤部は硬く，乳腺内の腫瘤部は相対的に軟らかく描出された．MRI，超音波検査，針生検の所見から，胸壁デスモイド腫瘍の乳腺浸潤が疑われた．大胸筋を一部含めた腫瘍摘出術を施行した．病理組織診断は異型の乏しい線維芽細胞様細胞で構成された病変で，免疫染色の結果からもデスモイド腫瘍と診断した．

We report a rare case of desmoid tumor in the chest wall with invasion into the left breast. A 30-year-old woman noticed a mass in her left breast in February 2006. She had a medical examination in our hospital in July 2006, when her breast pain had gradually become worse. At first, mammography showed neither a mass lesion nor bilateral malignant calcification. Ultrasonography showed an irregular hypoechoic mass occupying most of the deep breast tissue, a finding highly suggestive of scirrhous carcinoma. Fine-needle aspiration revealed a classII lesion with no cellular atypia. Core needle biopsy revealed proliferation of collagenous fiber and invasion of benign inflammatory cells. However, MRI showed gradual enhancement without a choline peak on MRS, indicative of benign fibrous tissue. For a second look, ultrasonography, elastography, and the finger compression maneuver were added. Elastography showed the mass lesion to cover a wide area on the chest wall and to be relatively harder than the mammary gland. These MRI ultrasonography, and fine needle biopsy findings led us to consider the possibility of a desmoid tumor. Resection of the mass lesion and part of the pectoralis major muscle was then carried out. Pathologic evaluation of the lumpectomy tissue with immunostaining showed a desmoid tumor comprising fibroblast-like cells.