剱 さおり¹, 角田 博子², 吉田 泰子¹, 八木下 和代², 野嵜 史³

Saori TSURUGI¹, Hiroko TSUNODA², Yasuko YOSHIDA¹, Kazuyo YAGISHITA², Fumi NOZAKI³

¹聖路加国際病院臨床検査科, ²聖路加国際病院放射線科, ³聖路加国際病院病理診断科

¹Clinical Laboratory Department, St. Luke's International Hospital, ²Department of Radiology, St. Luke's International Hospital, ³Department of Pathology, St. Luke's International Hospital

キーワード : breast cancer, breast ultrasound, elastography, distortion, normal variants

はじめに：乳房超音波検査において構築の乱れ様の低エコー所見であるにも関わらず，精検や経過観察から正常のバリエーションと判断できた症例を経験してきた．今回このような低エコー所見のどのような超音波所見に注意すれば正常のバリエーションとして精検不要とすることができるか検討した．対象と方法：2013年4月～2015年3月に施行された検診超音波で，一見癌に類似する構築の乱れ様の低エコー所見27名31所見を対象とした．その内訳は，精検の結果明らかな病変のなかった7所見と，精検不要として繰り返し受診により経過を追えた24所見である．これらを対象として超音波所見をretrospectiveに検討し，その後の経過も確認した．結果と考察：（1）クーパー靭帯による減弱ではない位置にも存在する（2）カラードプラにて分岐しない血管を認める（3） strain elastography施行全例で歪みの低下を認めないという共通した所見を認めた．分布は乳房の外側に多かった．細胞診あるいは針生検を施行した4所見はいずれも増殖性病変を認めなかった．中央値60ヵ月の経過中，精検例も含めた全例で癌発生は1例もないことが確認された．結論：構築の乱れ様の境界不明瞭な低エコー所見で一見癌に類似するもののなかに正常のバリエーションと判断してよいものがあることがわかった．不要な精検や組織診を回避するためにこのような症例を理解することは極めて重要である．

Purpose: We have encountered cases of hypoechoic lesions on breast ultrasonography that were diagnosed as normal anatomic variants based on further examinations or follow-up, despite the presence of distortion-like findings. In this study, we investigated what additional findings should be considered for such hypoechoic lesions to avoid unnecessary follow-up examinations. Subjects and Methods: In 27 patients with localized distortions suggestive of breast cancer during ultrasound screenings performed between April 2013 and March 2015, a total of 31 hypoechoic lesions were evaluated retrospectively. Seven of these 31 lesions did not show any obvious lesions on further examination, and 24 lesions did not require further examination and were followed up by repeat ultrasound. We retrospectively examined the ultrasound findings in these patients and confirmed their subsequent outcome. Results and Discussion: The common findings based on the 31 lesions were: (1) Its localization was not consistent with Cooper's ligaments in some cases, (2) unbranched vessels were observed on color Doppler imaging, and (3) no strain reduction was observed in any cases in which strain elastography was performed. These lesions were mostly located in the lateral part of the breast. No proliferative lesions were found among the four lesions in which we performed fine-needle aspiration biopsy or core needle biopsy. During a median follow-up of 60 months, no cancer was found in any of the cases, including those under scrutiny. Conclusion: Our study suggests that some of lesions with distortion-like findings resembling breast cancer on ultrasound are normal anatomic variants. It seems extremely important to understand such lesions to avoid unnecessary scrutiny and biopsy.