加藤 千絵子¹, 堀井 理絵^{2, 3}, 宮城 由美⁴, 國分 優美¹, 松枝 清¹, 上野 貴之⁴, 大野 真司⁴

Chieko KATO¹, Rie HORII^{2, 3}, Yumi MIYAGI⁴, Yumi KOKUBU¹, Kiyoshi MATSUEDA¹, Takayuki UENO⁴, Shinji OHNO⁴

¹がん研究会有明病院超音波検査部, ²がん研究会がん研究所病理部, ³埼玉県立がんセンター病理診断科埼玉県立がんセンター病理診断科, ⁴がん研究会有明病院乳腺センター

¹Department of Ultrasound, The Cancer Institute Hospital of Japanese Foundation for Cancer Research, ²Division of Pathology, The Cancer Institute, Japanese Foundation for Cancer Research, ³Department of Pathology, Saitama Cancer Center, ⁴Breast Oncology Center, The Cancer Institute Hospital of Japanese Foundation for Cancer Research

キーワード : breast cancer, invasive ductal carcinoma, ultrasonography, histological subtype

目的：乳癌取扱い規約の乳腺腫瘍の組織学的分類（規約分類）が2018年に改訂された．本研究は，規約分類の改訂が浸潤性乳管癌の超音波診断に与える影響を検討することを目的とした．対象と方法：旧分類で浸潤性乳管癌の乳頭腺管癌と診断された91例を対象に，超音波画像と手術材料の病理組織検体を見直し，新分類の各組織型における超音波画像の特徴を探った．結果と考察：対象例は新分類で微小浸潤癌26例（28.6％），乳管内成分優位の浸潤癌51例（56.0％），浸潤性乳管癌腺管形成型14例（15.4％）と診断された．超音波画像は41例（45.1％）で腫瘤，48例（52.7％）で非腫瘤性病変として認められ，2例（2.2％）は病変を指摘できなかった．新分類で微小浸潤癌と診断された症例中19例（73.1％）は非浸潤性乳管癌に類似した非腫瘤性病変の像を呈した．乳管内成分優位の浸潤癌のうち22例（43.1％）は腫瘤，27例（52.9％）は非腫瘤性病変として認められた．腺管形成型では12例（85.7％）は充実性腫瘤を呈し，うち7例（58.3％）で乳腺境界線の断裂を認め，浸潤癌の組織型推定は容易であった．多彩な超音波画像を示す旧分類の乳頭腺管癌は新分類で3つの組織型に分けられ，それらはそれぞれ特徴的な超音波画像を呈した．結論：新分類は超音波画像による組織型推定を行いやすい分類である．

Purpose: Histological classification of breast tumors edited by the Japanese Breast Cancer Society was revised in 2018. The purpose of this study was to clarify the impact of the revision on diagnostic imaging of invasive ductal carcinomas. Subjects and Methods: We investigated ultrasound images of 91 cases diagnosed as papillotubular carcinoma of invasive ductal carcinoma according to the old classification. Results and Discussion: The histological subtypes according to the new classification were microinvasive carcinoma in 26 cases (28.6%), invasive carcinoma with a predominant intraductal component in 51 cases (56.0%), and tubule forming type of invasive ductal carcinoma in 14 cases (15.4%). Ultrasound imaging showed a mass in 41 cases (45.1%) and a non-mass lesion in 48 cases (52.7%). In the remaining two cases, ultrasonography could not detect any abnormal findings. Of the microinvasive carcinoma cases, 19 cases (73.1%) showed a non-mass lesion that mimicked ductal carcinoma in situ. Ultrasound imaging of the cases diagnosed as invasive carcinoma with a predominant intraductal component revealed a mass in 22 cases (43.1%) and a non-mass lesion in 27 cases (52.9%). Twelve (85.7%) of the 14 cases with tubule forming type showed a solid mass. Of these, seven cases (58.3%) revealed discontinuity of borderline between mammary gland and fat tissue, suggesting invasive carcinoma. Papillotubular carcinomas showing various ultrasound images were divided into three histological types by the new classification, and each type showed characteristic ultrasound images. Conclusion: The new classification enables breast tumors to be correctly diagnosed by means of imaging.