白石 克子¹, 竹元 伸之², 山本 宏³, 大林 民典⁴

Katsuko SHIRAISHI¹, Nobuyuki TAKEMOTO², Hiroshi YAMAMOTO³, Taminori OBAYASHI⁴

¹さいたまセントラルクリニック臨床検査部門, ²ジャパンメディカルアライアンス東埼玉総合病院乳腺・内分泌外科, ³ジャパンメディカルアライアンス横浜市立脳卒中・神経脊椎センター介護老人保健施設コスモス, ⁴ジャパンメディカルアライアンス東埼玉総合病院臨床検査技術科

¹Department of Clinical Laboratory, Saitama Central Clinic, ²Department of Breast & Endocrine Surgery, Japan Medical Alliance East Saitama General Hospital, ³Geriatric Health Service Facility Yokohama Brain and Spine Center, Japan Medical Alliance, ⁴Department of Clinical Laboratory, Japan Medical Alliance East Saitama General Hospital

キーワード : xanthogranulomatous mastitis, ultrasonography

症例は60代，女性．X年12月左乳房腫瘤に気付き当院受診．前年度の乳がん検診では異常なし．視触診にて左乳房12時方向（A/C領域）に約2 cm大の弾性硬，表面不整，境界不明瞭，可動性不良な腫瘤を触知．MMGはカテゴリー1．乳房超音波検査Bモード法では，視触診指摘部位に19×10×16 mm，形状不整，境界明瞭粗造，内部エコーは嚢胞状変化を伴い不均一，後方エコー不変，前方境界線の断裂ははっきりせず，縦横比＝0.53，超音波ドプラ法では，血流信号を認めない腫瘤を指摘．造影CTでは，CD域に徐々に造影される10 mm程の不均一な結節を認めた．第一に乳がんを疑ったが確定に至らず針生検を施行．病理検査では，慢性炎症細胞およびマクロファージからなる黄色肉芽腫性炎症性病変の所見であり，追加で行った免疫染色でも腫瘍細胞を確認することはできなかった．経過観察で初診の翌年5月に施行した超音波検査では，腫瘤は16×7×14 mm，縦横比＝0.44と縮小．前回の形状に比べ，腫瘤中央部分は凹み前方への張り出しが消失．内部エコーは不均一な低エコーや線状高エコーを認めるものの，嚢胞部分は消失し，良性疾患を裏づける所見へと変化していた．黄色肉芽腫性炎症性病変は，乳腺での発生報告件数が極めて少なく，画像検査では悪性との鑑別が困難とされている．超音波検査所見の変化を中心に，文献的考察を含め報告する．

A woman in her 60s presented with a left breast tumor in December. No abnormality was identified during breast cancer screening performed the previous year. A poorly movable mass (2 cm in diameter), which was elastic firm and had an irregular and indistinct border, located at the 12 o'clock position (A/C area) in the left breast was identified by palpation. Mammography findings were category I. Breast B-mode ultrasonography revealed a tumor (19×10×16 mm) with an irregular shape, well-defined and rough border, hypoechoic heterogenous internal echo with cystic change, no change in posterior echoes, no interruption of the interface between adipose tissue and the gland, and D/W 0.53. Doppler ultrasonography revealed a tumor without blood flow signals. Contrast-enhanced computed tomography scan showed a heterogeneous nodule of about 10 mm in diameter gradually becoming enhanced in the CD area, a finding which is consistent with breast cancer. We first suspected breast cancer, but the pathological diagnosis based on a needle biopsy was xanthogranulomatous inflammatory lesions consisting of chronic inflammatory cells and macrophages, and tumor cells were not identified by additional immunostaining. Ultrasonography was performed in May the next year for follow-up purposes, and the tumor diameter and depth width ratio were confirmed to have decreased to 16×7×14 mm and 0.44, respectively. Compared with the previous shape, the central part of the tumor dimpled and the protrusion towards the front disappeared. Although an internal echo showed uneven low echoes and linear high echoes, the cystic region disappeared and changed to images suggestive of benign disease. Xanthogranulomatous inflammation is a very rare disease, and is difficult to distinguish from malignancy based on image examination. We thus report this case with a review of the literature, focusing on changes in ultrasonographic findings.